American Institute of Physics: Journal of Applied Physics: Table of Contents
Table of Contents for Journal of Applied Physics. List of articles from both the latest and ahead of print issues.
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American Institute of Physics: Journal of Applied Physics: Table of Contents
American Institute of Physics
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Journal of Applied Physics
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Moiré engineering in van der Waals heterostructures
https://aip.scitation.org/doi/10.1063/5.0105405?af=R&feed=mostrecent
Journal of Applied Physics, <a href="https://aip.scitation.org/toc/jap/132/12">Volume 132, Issue 12</a>, September 2022. <br/>Isolated atomic planes can be assembled into a multilayer van der Waals (vdW) heterostructure in a precisely chosen sequence. These heterostructures feature moiré patterns if the constituent 2D material layers are stacked in an incommensurable way, due to a lattice mismatch or twist. This designbystacking has opened up the promising area of moiré engineering, a term that can be understood in two different perspectives, namely, (i) structural—engineering a moiré pattern by introducing twist, relative strain, or defects that affect the commensurability of the layers and (ii) functional—exploiting a moiré pattern to find and tune resulting physical properties of a vdW heterostructure. The latter meaning, referring to the application of a moiré pattern, is seen in the literature in the specific context of the observation of correlated electronic states and unconventional superconductivity in twisted bilayer graphene. The former meaning, referring to the design of the moiré pattern itself, is present in the literature but less commonly discussed or less understood. The underlying link between these two perspectives lies in the deformation field of the moiré superlattice. In this Perspective, we describe a path from designing a moiré pattern to employing the moiré pattern to tune physical properties of a vdW heterostructure. We also discuss the concept of moiré engineering in the context of twistronics, strain engineering, and defect engineering in vdW heterostructures. Although twistronics is always associated with moiré superlattices, strain and defect engineering are often not. Here, we demonstrate how strain and defect engineering can be understood within the context of moiré engineering. Adopting this perspective, we note that moiré engineering creates a compelling opportunity to design and develop multiscale electronic devices.
Journal of Applied Physics, Volume 132, Issue 12, September 2022. <br/>Isolated atomic planes can be assembled into a multilayer van der Waals (vdW) heterostructure in a precisely chosen sequence. These heterostructures feature moiré patterns if the constituent 2D material layers are stacked in an incommensurable way, due to a lattice mismatch or twist. This designbystacking has opened up the promising area of moiré engineering, a term that can be understood in two different perspectives, namely, (i) structural—engineering a moiré pattern by introducing twist, relative strain, or defects that affect the commensurability of the layers and (ii) functional—exploiting a moiré pattern to find and tune resulting physical properties of a vdW heterostructure. The latter meaning, referring to the application of a moiré pattern, is seen in the literature in the specific context of the observation of correlated electronic states and unconventional superconductivity in twisted bilayer graphene. The former meaning, referring to the design of the moiré pattern itself, is present in the literature but less commonly discussed or less understood. The underlying link between these two perspectives lies in the deformation field of the moiré superlattice. In this Perspective, we describe a path from designing a moiré pattern to employing the moiré pattern to tune physical properties of a vdW heterostructure. We also discuss the concept of moiré engineering in the context of twistronics, strain engineering, and defect engineering in vdW heterostructures. Although twistronics is always associated with moiré superlattices, strain and defect engineering are often not. Here, we demonstrate how strain and defect engineering can be understood within the context of moiré engineering. Adopting this perspective, we note that moiré engineering creates a compelling opportunity to design and develop multiscale electronic devices.
Moiré engineering in van der Waals heterostructures
10.1063/5.0105405
Journal of Applied Physics
20220926T09:33:14Z
© 2022 Author(s).
Tawfiqur Rakib
Pascal Pochet
Elif Ertekin
Harley T. Johnson

Coupling of ferroelectric and valley properties in 2D materials
https://aip.scitation.org/doi/10.1063/5.0112893?af=R&feed=mostrecent
Journal of Applied Physics, <a href="https://aip.scitation.org/toc/jap/132/12">Volume 132, Issue 12</a>, September 2022. <br/>Twodimensional (2D) valleytronic materials are both fundamentally intriguing and practically appealing to explore novel physics and design nextgeneration devices. However, traditional control means such as optic pumping or magnetic field cannot meet the demands of modern electron devices for miniaturization, lowdissipation, and nonvolatility. Thus, it is attractive to combine the ferroelectric property with valley property in a single compound. In this paper, the recent progress of ferroelectricvalley coupling is reviewed. First, we briefly recall the development of valleytronics in the past several years. Then, various structures demonstrating ferroelectricvalley coupling, including heterostructures and intrinsic materials, are introduced. Subsequently, we describe ferroelectricvalley coupling in sliding and adsorption system and the unconventional ferroelectricity in the moiré system. Finally, we discuss the research status and outlook. We hope that this perspective will be helpful to bridge the gap between valleytronics and ferroelectrics in 2D materials and inspire further exciting findings.
Journal of Applied Physics, Volume 132, Issue 12, September 2022. <br/>Twodimensional (2D) valleytronic materials are both fundamentally intriguing and practically appealing to explore novel physics and design nextgeneration devices. However, traditional control means such as optic pumping or magnetic field cannot meet the demands of modern electron devices for miniaturization, lowdissipation, and nonvolatility. Thus, it is attractive to combine the ferroelectric property with valley property in a single compound. In this paper, the recent progress of ferroelectricvalley coupling is reviewed. First, we briefly recall the development of valleytronics in the past several years. Then, various structures demonstrating ferroelectricvalley coupling, including heterostructures and intrinsic materials, are introduced. Subsequently, we describe ferroelectricvalley coupling in sliding and adsorption system and the unconventional ferroelectricity in the moiré system. Finally, we discuss the research status and outlook. We hope that this perspective will be helpful to bridge the gap between valleytronics and ferroelectrics in 2D materials and inspire further exciting findings.
Coupling of ferroelectric and valley properties in 2D materials
10.1063/5.0112893
Journal of Applied Physics
20220928T11:37:29Z
© 2022 Author(s).
JunDing Zheng
YiFeng Zhao
YiFan Tan
Zhao Guan
Ni Zhong
FangYu Yue
PingHua Xiang
ChunGang Duan

Optical spectroscopy combined in situ with instrumented indentation
https://aip.scitation.org/doi/10.1063/5.0099166?af=R&feed=mostrecent
Journal of Applied Physics, <a href="https://aip.scitation.org/toc/jap/132/12">Volume 132, Issue 12</a>, September 2022. <br/>Modern trends in the development of experimental research methods imply not only an increase in the accuracy of a specific technique but also the possibility of combining diverse measurements in the course of one experiment. While optical spectroscopy remains one of the most powerful tools used in the chemical and physical sciences to study the structure of a wide range of materials, it is impossible to imagine a single study of local mechanical properties without instrumental indentation. A powerful investigation technique is the in situ combination of these two methods within one experiment. This can be made by focusing the laser either through the transparent sample or through the transparent indenter tip of the special geometry preventing the total internal reflection in diamond. This Tutorial discusses the preparation and characterization of such a transparent diamond indenter. The obtained experimental results and promising application areas of simultaneous measurement of optical spectra during indentation are considered.
Journal of Applied Physics, Volume 132, Issue 12, September 2022. <br/>Modern trends in the development of experimental research methods imply not only an increase in the accuracy of a specific technique but also the possibility of combining diverse measurements in the course of one experiment. While optical spectroscopy remains one of the most powerful tools used in the chemical and physical sciences to study the structure of a wide range of materials, it is impossible to imagine a single study of local mechanical properties without instrumental indentation. A powerful investigation technique is the in situ combination of these two methods within one experiment. This can be made by focusing the laser either through the transparent sample or through the transparent indenter tip of the special geometry preventing the total internal reflection in diamond. This Tutorial discusses the preparation and characterization of such a transparent diamond indenter. The obtained experimental results and promising application areas of simultaneous measurement of optical spectra during indentation are considered.
Optical spectroscopy combined in situ with instrumented indentation
10.1063/5.0099166
Journal of Applied Physics
20220922T09:48:00Z
© 2022 Author(s).
A. Useinov
V. Reshetov
A. Gusev
E. Gladkih

Spontaneous polarization in van der Waals materials: Twodimensional ferroelectrics and device applications
https://aip.scitation.org/doi/10.1063/5.0116445?af=R&feed=mostrecent
Journal of Applied Physics, <a href="https://aip.scitation.org/toc/jap/132/12">Volume 132, Issue 12</a>, September 2022. <br/>The research on twodimensional (2D) van der Waals ferroelectrics has grown substantially in the last decade. These layered materials differ from conventional thinfilm oxide ferroelectrics in that the surface and interface are free from dangling bonds. Some may also possess uncommon properties, such as bandgap tunability, mechanical flexibility, and high carrier mobility, which are desirable for applications in nanoelectronics and optoelectronics. This Tutorial starts by reviewing the theoretical tools in 2D ferroelectric studies, followed by discussing the material synthesis and sample characterization. Several prototypical electronic devices with innovative functionalities will be highlighted. Readers can use this article to obtain a basic understanding of the current status, challenges, and future prospects of 2D ferroelectric materials.
Journal of Applied Physics, Volume 132, Issue 12, September 2022. <br/>The research on twodimensional (2D) van der Waals ferroelectrics has grown substantially in the last decade. These layered materials differ from conventional thinfilm oxide ferroelectrics in that the surface and interface are free from dangling bonds. Some may also possess uncommon properties, such as bandgap tunability, mechanical flexibility, and high carrier mobility, which are desirable for applications in nanoelectronics and optoelectronics. This Tutorial starts by reviewing the theoretical tools in 2D ferroelectric studies, followed by discussing the material synthesis and sample characterization. Several prototypical electronic devices with innovative functionalities will be highlighted. Readers can use this article to obtain a basic understanding of the current status, challenges, and future prospects of 2D ferroelectric materials.
Spontaneous polarization in van der Waals materials: Twodimensional ferroelectrics and device applications
10.1063/5.0116445
Journal of Applied Physics
20220926T12:47:15Z
© 2022 Author(s).
Keji Lai

Mechanical characterization of piezoelectric materials: A perspective on deformation behavior across different microstructural length scales
https://aip.scitation.org/doi/10.1063/5.0099161?af=R&feed=mostrecent
Journal of Applied Physics, <a href="https://aip.scitation.org/toc/jap/132/12">Volume 132, Issue 12</a>, September 2022. <br/>Piezoelectric materials (PEMs) find a wide spectrum of applications that include, but are not limited to, sensors, actuators, semiconductors, memory devices, and energy harvesting systems due to their outstanding electromechanical and polarization characteristics. Notably, these PEMs can be employed across several length scales (both intrinsic and extrinsic) ranging from mesoscale (bulk ceramics) to nanoscale (thin films) during their applications. Over the years, progress in probing individual electrical and mechanical properties of PEM has been notable. However, proportional review articles providing the mechanical characterization of PEM are relatively few. The present article aims to give a tutorial on the mechanical testing of PEMs, ranging from the conventional bulk deformation experiments to the most recent smallscale testing techniques from a materials science perspective. The advent of nanotechnology has led materials scientists to develop in situ testing techniques to probe the realtime electromechanical behavior of PEMs. Therefore, this article presents a systematic outlook on ex situ and in situ deformation experiments in mechanical and electromechanical environments, related mechanical behavior, and ferroelectric/elastic distortion during deformation. The first part provides significant insights into the multifunctionality of PEM and various contributing microstructural length scales, followed by a motivation to characterize the mechanical properties from the application's point of view. In the midst, the mechanical behavior of PEM and related mechanical characterization techniques (from mesoscale to nanoscale) are highlighted. The last part summarizes current challenges, future perspectives, and important observations.
Journal of Applied Physics, Volume 132, Issue 12, September 2022. <br/>Piezoelectric materials (PEMs) find a wide spectrum of applications that include, but are not limited to, sensors, actuators, semiconductors, memory devices, and energy harvesting systems due to their outstanding electromechanical and polarization characteristics. Notably, these PEMs can be employed across several length scales (both intrinsic and extrinsic) ranging from mesoscale (bulk ceramics) to nanoscale (thin films) during their applications. Over the years, progress in probing individual electrical and mechanical properties of PEM has been notable. However, proportional review articles providing the mechanical characterization of PEM are relatively few. The present article aims to give a tutorial on the mechanical testing of PEMs, ranging from the conventional bulk deformation experiments to the most recent smallscale testing techniques from a materials science perspective. The advent of nanotechnology has led materials scientists to develop in situ testing techniques to probe the realtime electromechanical behavior of PEMs. Therefore, this article presents a systematic outlook on ex situ and in situ deformation experiments in mechanical and electromechanical environments, related mechanical behavior, and ferroelectric/elastic distortion during deformation. The first part provides significant insights into the multifunctionality of PEM and various contributing microstructural length scales, followed by a motivation to characterize the mechanical properties from the application's point of view. In the midst, the mechanical behavior of PEM and related mechanical characterization techniques (from mesoscale to nanoscale) are highlighted. The last part summarizes current challenges, future perspectives, and important observations.
Mechanical characterization of piezoelectric materials: A perspective on deformation behavior across different microstructural length scales
10.1063/5.0099161
Journal of Applied Physics
20220926T12:47:12Z
© 2022 Author(s).
V. S. Kathavate
K. Eswar Prasad
Mangalampalli S. R. N. Kiran
Yong Zhu

Temperaturesensitive hybridization of propagating and localized surface phonon polaritons in polar 4HSiC nanoresonators
https://aip.scitation.org/doi/10.1063/5.0107295?af=R&feed=mostrecent
Journal of Applied Physics, <a href="https://aip.scitation.org/toc/jap/132/12">Volume 132, Issue 12</a>, September 2022. <br/>Polar 4HSiC nanoresonators can host localized surface phonon polaritons (SPhPs) with low optical loss and fully exploit light–matter interactions for promising nanophotonic applications such as surfaceenhanced spectroscopies and thermal imaging. To expand the midinfrared and infrared application spaces, a sound knowledge of temperature effect on infrared dielectric functions and SPhPs of 4HSiC is required, yet it remains largely unexplored. Herein, we focus on exploiting the temperature influence on dielectric functions, hybridization of propagating and localized SPhPs, and tailed spectral radiation properties of 4HSiC nanopillar arrays through spectroscopic ellipsometry (SE) measurements as well as multiscale simulations. The 4HSiC crystal is grown using the physical vapor transport method, and SE experiments measure infrared dielectric functions at temperatures between 300 and 800 K. Finiteelement electromagnetic simulations confirm the emerged Monopole and transverse dipoles (TD1 and TD2) resonance modes in 4HSiC nanoresonators, which agrees with the literature experiment. At high temperatures with strong lattice vibration, the amplitudes of resonant optical absorption peaks gradually decrease and the linewidths broaden, accompanied by the weakened electric resonances. Firstprinciples calculations show that the anharmonic phonon scattering strengthens and less optical phonons are coupled to incident photons as temperature increases. Moreover, the propagating and localized SPhPs’ hybridization and spectral radiation properties of 4HSiC nanopillar arrays can be largely tailed by modifying the morphology and incident angle of light. This work provides physical insights into the temperatureinduced spectral tuning of 4HSiC nanoresonators and helps exploit their applications in the hightemperature working conditions.
Journal of Applied Physics, Volume 132, Issue 12, September 2022. <br/>Polar 4HSiC nanoresonators can host localized surface phonon polaritons (SPhPs) with low optical loss and fully exploit light–matter interactions for promising nanophotonic applications such as surfaceenhanced spectroscopies and thermal imaging. To expand the midinfrared and infrared application spaces, a sound knowledge of temperature effect on infrared dielectric functions and SPhPs of 4HSiC is required, yet it remains largely unexplored. Herein, we focus on exploiting the temperature influence on dielectric functions, hybridization of propagating and localized SPhPs, and tailed spectral radiation properties of 4HSiC nanopillar arrays through spectroscopic ellipsometry (SE) measurements as well as multiscale simulations. The 4HSiC crystal is grown using the physical vapor transport method, and SE experiments measure infrared dielectric functions at temperatures between 300 and 800 K. Finiteelement electromagnetic simulations confirm the emerged Monopole and transverse dipoles (TD1 and TD2) resonance modes in 4HSiC nanoresonators, which agrees with the literature experiment. At high temperatures with strong lattice vibration, the amplitudes of resonant optical absorption peaks gradually decrease and the linewidths broaden, accompanied by the weakened electric resonances. Firstprinciples calculations show that the anharmonic phonon scattering strengthens and less optical phonons are coupled to incident photons as temperature increases. Moreover, the propagating and localized SPhPs’ hybridization and spectral radiation properties of 4HSiC nanopillar arrays can be largely tailed by modifying the morphology and incident angle of light. This work provides physical insights into the temperatureinduced spectral tuning of 4HSiC nanoresonators and helps exploit their applications in the hightemperature working conditions.
Temperaturesensitive hybridization of propagating and localized surface phonon polaritons in polar 4HSiC nanoresonators
10.1063/5.0107295
Journal of Applied Physics
20220923T09:51:49Z
© 2022 Author(s).
Tianhao Fei
Tao Cheng
Huanhuan Zhao
Xuejian Xie
Lei Zhang
Zhiwei Fu
JiaYue Yang
Linhua Liu

Angleresolved highorder harmonics in wurtzitetype ZnO
https://aip.scitation.org/doi/10.1063/5.0098582?af=R&feed=mostrecent
Journal of Applied Physics, <a href="https://aip.scitation.org/toc/jap/132/12">Volume 132, Issue 12</a>, September 2022. <br/>Highorder harmonics in solids provide a method of analyzing the intraband and interband dynamics of a solid driven by an ultrafast laser. This study analyzed the contributions of intraband and interband dynamics based on angleresolved highorder harmonics. According to the simulations and experiments, we found that the angular divergences of the harmonics have an evident boundary at the bandgap when the laser is polarized along the asymmetric direction, which is primarily invoked by the interplay of an interband transition and an intraband electron movement, and the intraband and interband dynamics have different sensitivities of the spatial phase of driving laser.
Journal of Applied Physics, Volume 132, Issue 12, September 2022. <br/>Highorder harmonics in solids provide a method of analyzing the intraband and interband dynamics of a solid driven by an ultrafast laser. This study analyzed the contributions of intraband and interband dynamics based on angleresolved highorder harmonics. According to the simulations and experiments, we found that the angular divergences of the harmonics have an evident boundary at the bandgap when the laser is polarized along the asymmetric direction, which is primarily invoked by the interplay of an interband transition and an intraband electron movement, and the intraband and interband dynamics have different sensitivities of the spatial phase of driving laser.
Angleresolved highorder harmonics in wurtzitetype ZnO
10.1063/5.0098582
Journal of Applied Physics
20220926T09:33:18Z
© 2022 Author(s).
Wenkai Li
Zhe Liu
Beijie Shao
Junyu Qian
Yanyan Li
Yujie Peng
Yuxin Leng

Simultaneous application of photon Doppler velocimetry and coherent backscattering for probing ejecta from shockloaded samples
https://aip.scitation.org/doi/10.1063/5.0104721?af=R&feed=mostrecent
Journal of Applied Physics, <a href="https://aip.scitation.org/toc/jap/132/12">Volume 132, Issue 12</a>, September 2022. <br/>We present the results of experiments on simultaneous probing of a shockloaded layer of aluminum oxide particles by the methods of photon Doppler velocimetry (PDV) and coherent backscattering (CBS). The measurements of the angular profiles of CBS from a dynamically expanding medium are reported for the first time. The powder of particles was applied to the surface of an explosively driven steel plate. The particle velocities ranged from [math] to [math] km/s. The main characteristics of the cloud of ejected particles (the areal density, mass–velocity distribution, etc.) are recovered from the PDV and CBS probing data using an approach based on theoretical modeling of the measurement results with the transport equation. By varying the parameters of the particle cloud (the transport optical thickness and the parameters of the initial velocity distribution), it is managed to fit the dynamics of the calculated Doppler spectra and CBS angular profiles to the data of measurements in given time intervals and, thereby, recover the values of these parameters. As applied to the diagnostics of ejecta from shockloaded samples, the CBS method is shown to provide independent data on the spatial distribution of particles over the cloud thickness. The presented results demonstrate that the joint application of PDV and CBSbased channels of measurements to ejecta diagnostics makes it possible to halve the error in recovering the ejecta parameters compared to using PDV alone.
Journal of Applied Physics, Volume 132, Issue 12, September 2022. <br/>We present the results of experiments on simultaneous probing of a shockloaded layer of aluminum oxide particles by the methods of photon Doppler velocimetry (PDV) and coherent backscattering (CBS). The measurements of the angular profiles of CBS from a dynamically expanding medium are reported for the first time. The powder of particles was applied to the surface of an explosively driven steel plate. The particle velocities ranged from [math] to [math] km/s. The main characteristics of the cloud of ejected particles (the areal density, mass–velocity distribution, etc.) are recovered from the PDV and CBS probing data using an approach based on theoretical modeling of the measurement results with the transport equation. By varying the parameters of the particle cloud (the transport optical thickness and the parameters of the initial velocity distribution), it is managed to fit the dynamics of the calculated Doppler spectra and CBS angular profiles to the data of measurements in given time intervals and, thereby, recover the values of these parameters. As applied to the diagnostics of ejecta from shockloaded samples, the CBS method is shown to provide independent data on the spatial distribution of particles over the cloud thickness. The presented results demonstrate that the joint application of PDV and CBSbased channels of measurements to ejecta diagnostics makes it possible to halve the error in recovering the ejecta parameters compared to using PDV alone.
Simultaneous application of photon Doppler velocimetry and coherent backscattering for probing ejecta from shockloaded samples
10.1063/5.0104721
Journal of Applied Physics
20220926T09:33:16Z
© 2022 Author(s).
A. V. Andriyash
Sh. M. Ismailov
V. G. Kamenev
G. V. Kaplukov
A. N. Kondratev
P. V. Kubasov
S. E. Kuratov
D. B. Rogozkin
A. A. Tikhov
I. V. Tur
A. S. Shubin
S. A. Shubin
P. N. Yaroschuk

Magnomechanically induced absorption and switching properties in a dispersively coupled magnonqubit system
https://aip.scitation.org/doi/10.1063/5.0111516?af=R&feed=mostrecent
Journal of Applied Physics, <a href="https://aip.scitation.org/toc/jap/132/12">Volume 132, Issue 12</a>, September 2022. <br/>We theoretically study the nonlinear behavior of a hybrid quantum magnomechanical system, where the system consisting of a superconducting qubit couples dispersively to a magnon–phonon mode. The magnetic excitations (magnons) can interact with the mechanical vibrations of the system via a magnomechanical interaction, which results in the formation of magnomechanically induced transparency in the output of the system. We investigate the system’s switching behavior in the dressed qubit anharmonicity of the system and shows the sharp bistable frequency switching of the magnon–excitons. The proposed model also shows a realistic scheme to measure the magnonqubit dispersive shift in the absorption spectra of the probe field. The absorption spectrum induced by the dispersive coupling shows a series of asymmetric double Fano line shapes whose positions can be determined by the magnonqubit driving field. Our results will provide a theoretical approach to understand the complex and dynamic nonlinear interactions and may come up with great significance in the realization of quantum sensing applications of magnonic systems.
Journal of Applied Physics, Volume 132, Issue 12, September 2022. <br/>We theoretically study the nonlinear behavior of a hybrid quantum magnomechanical system, where the system consisting of a superconducting qubit couples dispersively to a magnon–phonon mode. The magnetic excitations (magnons) can interact with the mechanical vibrations of the system via a magnomechanical interaction, which results in the formation of magnomechanically induced transparency in the output of the system. We investigate the system’s switching behavior in the dressed qubit anharmonicity of the system and shows the sharp bistable frequency switching of the magnon–excitons. The proposed model also shows a realistic scheme to measure the magnonqubit dispersive shift in the absorption spectra of the probe field. The absorption spectrum induced by the dispersive coupling shows a series of asymmetric double Fano line shapes whose positions can be determined by the magnonqubit driving field. Our results will provide a theoretical approach to understand the complex and dynamic nonlinear interactions and may come up with great significance in the realization of quantum sensing applications of magnonic systems.
Magnomechanically induced absorption and switching properties in a dispersively coupled magnonqubit system
10.1063/5.0111516
Journal of Applied Physics
20220926T09:33:14Z
© 2022 Author(s).
Sabur A. Barbhuiya
Aranya B. Bhattacherjee

Impact of 100 MeV highenergy proton irradiation on βGa2O3 solarblind photodetector: Oxygen vacancies formation and resistance switching effect
https://aip.scitation.org/doi/10.1063/5.0105752?af=R&feed=mostrecent
Journal of Applied Physics, <a href="https://aip.scitation.org/toc/jap/132/12">Volume 132, Issue 12</a>, September 2022. <br/>βGa2O3 based solarblind photodetectors have strong radiation hardness and great potential applications in Earth's space environment due to the large bandgap and high bond energy. In this work, we investigated the photoelectric properties influence of βGa2O3 photodetector irradiated by 100 MeV highenergy protons which are the primary components in the inner belt of the Van Allen radiation belts where solarblind photodetectors mainly worked. After proton irradiation, due to the formation of more oxygen vacancies and their migration driven by bias at the metal/semiconductor interface, transportation of carriers transforms with electron tunneling conduction for lowresistance state and thermionic emission for high resistance state. As a result, the current–voltage curves of βGa2O3 solarblind photodetectors exhibit apparent hysteresis loops. The photoresponsivity of βGa2O3 photodetectors slightly increases from 1.2 × 103 to 1.4 × 103 A/W after irradiation, and the photoresponse speed becomes faster at a negative voltage while slower at positive voltage. The results reveal the effects of highenergy proton irradiation on βGa2O3 solarblind photodetectors and provide a basis for the study of their use in a radiation harsh environment.
Journal of Applied Physics, Volume 132, Issue 12, September 2022. <br/>βGa2O3 based solarblind photodetectors have strong radiation hardness and great potential applications in Earth's space environment due to the large bandgap and high bond energy. In this work, we investigated the photoelectric properties influence of βGa2O3 photodetector irradiated by 100 MeV highenergy protons which are the primary components in the inner belt of the Van Allen radiation belts where solarblind photodetectors mainly worked. After proton irradiation, due to the formation of more oxygen vacancies and their migration driven by bias at the metal/semiconductor interface, transportation of carriers transforms with electron tunneling conduction for lowresistance state and thermionic emission for high resistance state. As a result, the current–voltage curves of βGa2O3 solarblind photodetectors exhibit apparent hysteresis loops. The photoresponsivity of βGa2O3 photodetectors slightly increases from 1.2 × 103 to 1.4 × 103 A/W after irradiation, and the photoresponse speed becomes faster at a negative voltage while slower at positive voltage. The results reveal the effects of highenergy proton irradiation on βGa2O3 solarblind photodetectors and provide a basis for the study of their use in a radiation harsh environment.
Impact of 100 MeV highenergy proton irradiation on βGa2O3 solarblind photodetector: Oxygen vacancies formation and resistance switching effect
10.1063/5.0105752
Journal of Applied Physics
20220928T11:37:26Z
© 2022 Author(s).
M. M. Chang
D. Y. Guo
X. L. Zhong
F. B. Zhang
J. B. Wang

Lowpower, highperformance, and smallfootprint, singlepump optical parametric amplifier for photonic integrated circuits
https://aip.scitation.org/doi/10.1063/5.0109517?af=R&feed=mostrecent
Journal of Applied Physics, <a href="https://aip.scitation.org/toc/jap/132/12">Volume 132, Issue 12</a>, September 2022. <br/>A singlepump optical parametric amplifier (OPA) is modeled using a ptoluene sulfonate (PTS) filled siliconbased slotted photonic crystal waveguide (SPCW). The PTSSPCW has CMOSprocess compatibility and offers slowlight enhanced nonlinearity of PTS due to extreme optical confinement in SPCW. The adverse effects of twophoton absorption and free carrier absorption are absent in PTS in the standard optical communication window. The coupled nonlinear Schrödinger’s equations have been modified to analyze the OPA under slowlight propagation. Performances of the OPA are evaluated in both the high and low dispersive zones of the structure. The high dispersive zone exhibits high group indices to the operating waves, leading to a high parametric gain ([math] dB) and high conversion efficiency ([math] dB) utilizing a 350 [math] long PTSSPCW and a pump power of 65 mW. However, this zone degrades the shape of a [math] ps pulse due to selfphase and crossphase modulation. On the other hand, in the low dispersive zone, a similar parametric gain and conversion efficiency (both [math] dB) are attained utilizing a 1250 [math] long PTSSPCW and a pump power of 150 mW. Nevertheless, this zone degrades a 5 ps pulse only after a distance of 1500 [math]. The analyses show a 30 nm bandwidth considering a gain above 30 dB. Investigation of the effect of fabrication imperfections shows excellent performance sustainability of the OPA up to a random error of 40 nm. These remarkable performances make this lowpowered, smallfootprint OPA suitable for achieving tunable optical amplification in photonic integrated circuits.
Journal of Applied Physics, Volume 132, Issue 12, September 2022. <br/>A singlepump optical parametric amplifier (OPA) is modeled using a ptoluene sulfonate (PTS) filled siliconbased slotted photonic crystal waveguide (SPCW). The PTSSPCW has CMOSprocess compatibility and offers slowlight enhanced nonlinearity of PTS due to extreme optical confinement in SPCW. The adverse effects of twophoton absorption and free carrier absorption are absent in PTS in the standard optical communication window. The coupled nonlinear Schrödinger’s equations have been modified to analyze the OPA under slowlight propagation. Performances of the OPA are evaluated in both the high and low dispersive zones of the structure. The high dispersive zone exhibits high group indices to the operating waves, leading to a high parametric gain ([math] dB) and high conversion efficiency ([math] dB) utilizing a 350 [math] long PTSSPCW and a pump power of 65 mW. However, this zone degrades the shape of a [math] ps pulse due to selfphase and crossphase modulation. On the other hand, in the low dispersive zone, a similar parametric gain and conversion efficiency (both [math] dB) are attained utilizing a 1250 [math] long PTSSPCW and a pump power of 150 mW. Nevertheless, this zone degrades a 5 ps pulse only after a distance of 1500 [math]. The analyses show a 30 nm bandwidth considering a gain above 30 dB. Investigation of the effect of fabrication imperfections shows excellent performance sustainability of the OPA up to a random error of 40 nm. These remarkable performances make this lowpowered, smallfootprint OPA suitable for achieving tunable optical amplification in photonic integrated circuits.
Lowpower, highperformance, and smallfootprint, singlepump optical parametric amplifier for photonic integrated circuits
10.1063/5.0109517
Journal of Applied Physics
20220930T09:46:21Z
© 2022 Author(s).
Shatrughna Kumar
Mrinal Sen

Thunder acoustic signature for channel reconstruction in triggered lightning
https://aip.scitation.org/doi/10.1063/5.0110866?af=R&feed=mostrecent
Journal of Applied Physics, <a href="https://aip.scitation.org/toc/jap/132/12">Volume 132, Issue 12</a>, September 2022. <br/>There are few reports on the nearfield acoustic signals corresponding to lightning return strokes. One rockettriggered lightning flash, which contains 13 return strokes, initial continuous current (ICC) processes, and abundant Mcomponents, was observed in the summer of 2018 and reported in this study. The complete nearfield acoustic pressure signals initiated by the flash were recorded and analyzed. It is found that the nearfield acoustic pressure signals from each return stroke are composed of the first arrived Nshape shock waveform and the subsequent lowfrequency oscillating waveforms. The characteristic of the acoustic waveforms has been parametrically defined and quantitatively analyzed, with a comprehensively acousticelectrical correlation investigation. The acoustic pressure signals from intensive ICC processes and Mcomponent pulses with different discharge intensities are also discussed. It is found that the tooclose time interval between Mcomponent and previous current pulses would affect the generation and measurement of the acoustic pressure waveforms from the Mcomponent, even though the discharge amplitude is competitive and the wavefront is fast. The same phenomenon has also been observed in the acoustic signals from a return stroke with a too close interval from the previous pulse. The acoustic source localization with great accuracy for lightning channel reconstruction was realized based on the measured acoustic signals. The reconstructed channel structure agrees with that of the synchronously captured optical image. The study of the characteristics of acoustic signals from lightning discharge contributes to the recognition of thunder signals, source localization for channel reconstruction, and understanding of the lightning discharge process.
Journal of Applied Physics, Volume 132, Issue 12, September 2022. <br/>There are few reports on the nearfield acoustic signals corresponding to lightning return strokes. One rockettriggered lightning flash, which contains 13 return strokes, initial continuous current (ICC) processes, and abundant Mcomponents, was observed in the summer of 2018 and reported in this study. The complete nearfield acoustic pressure signals initiated by the flash were recorded and analyzed. It is found that the nearfield acoustic pressure signals from each return stroke are composed of the first arrived Nshape shock waveform and the subsequent lowfrequency oscillating waveforms. The characteristic of the acoustic waveforms has been parametrically defined and quantitatively analyzed, with a comprehensively acousticelectrical correlation investigation. The acoustic pressure signals from intensive ICC processes and Mcomponent pulses with different discharge intensities are also discussed. It is found that the tooclose time interval between Mcomponent and previous current pulses would affect the generation and measurement of the acoustic pressure waveforms from the Mcomponent, even though the discharge amplitude is competitive and the wavefront is fast. The same phenomenon has also been observed in the acoustic signals from a return stroke with a too close interval from the previous pulse. The acoustic source localization with great accuracy for lightning channel reconstruction was realized based on the measured acoustic signals. The reconstructed channel structure agrees with that of the synchronously captured optical image. The study of the characteristics of acoustic signals from lightning discharge contributes to the recognition of thunder signals, source localization for channel reconstruction, and understanding of the lightning discharge process.
Thunder acoustic signature for channel reconstruction in triggered lightning
10.1063/5.0110866
Journal of Applied Physics
20220928T11:37:20Z
© 2022 Author(s).
Jianguo Wang
Jinxin Cao
Li Cai
Rui Su
Mi Zhou
Yadong Fan
Quanxin Li

Spin wave dispersion relations and isofrequency curve calculations using micromagnetic simulations
https://aip.scitation.org/doi/10.1063/5.0101394?af=R&feed=mostrecent
Journal of Applied Physics, <a href="https://aip.scitation.org/toc/jap/132/12">Volume 132, Issue 12</a>, September 2022. <br/>Dispersion relations and isofrequency curves are of critical importance for understanding the behavior of waves, including what frequencies can be excited, how the waves will propagate, and how waves in one system will couple to another. Here, we present methods to extract the dispersion relations and isofrequency curves automatically and conveniently, each from a single micromagnetic simulation run. These methods have significant advantages in that they provide a means to obtain rapid insight into spin wave behavior in complex situations where analytic approaches are difficult or impossible. We present multiple examples to illustrate the methodology and discuss specific issues that need to be considered for the different situations.
Journal of Applied Physics, Volume 132, Issue 12, September 2022. <br/>Dispersion relations and isofrequency curves are of critical importance for understanding the behavior of waves, including what frequencies can be excited, how the waves will propagate, and how waves in one system will couple to another. Here, we present methods to extract the dispersion relations and isofrequency curves automatically and conveniently, each from a single micromagnetic simulation run. These methods have significant advantages in that they provide a means to obtain rapid insight into spin wave behavior in complex situations where analytic approaches are difficult or impossible. We present multiple examples to illustrate the methodology and discuss specific issues that need to be considered for the different situations.
Spin wave dispersion relations and isofrequency curve calculations using micromagnetic simulations
10.1063/5.0101394
Journal of Applied Physics
20220922T09:48:01Z
© 2022 Author(s).
Matthew G. Copus
Alexandra R. Stuart
Robert E. Camley
Kristen S. Buchanan

Filmpenetrating transducers applicable to onchip reservoir computing with spin waves
https://aip.scitation.org/doi/10.1063/5.0102974?af=R&feed=mostrecent
Journal of Applied Physics, <a href="https://aip.scitation.org/toc/jap/132/12">Volume 132, Issue 12</a>, September 2022. <br/>We have proposed a spinwave transducer structure named filmpenetrating transducers (FPTs). FPTs penetrate an onchip magnetic film for a spinwave transmission medium and allow flexible spatial arrangements of many exciters/detectors due to their zerodimensional feature. We constructed four device models with different spatial arrangements of FPT/conventional exciters using a 10nmthick ferrimagnetic garnet film with a central FPT detector. We performed numerical experiments that combine electromagnetics with micromagnetics including thermal noise at 300 K. We evaluated important device features of FPTs, such as the signaltonoise ratios (SNRs), input/output signal transmission efficiencies, and nonlinear phenomena of spin waves. We applied inphase sinusoidal input currents with various amplitudes and frequencies and altered the damping strengths near the film boundaries. We obtained sufficient SNRs for the practical use of FPTs and revealed that FPTs have both higher transmission efficiencies and nonlinear strengths than conventional antennas, as the input frequency approaches the ferromagnetic resonance frequency of the film. Moreover, we observed and analyzed various nonlinear phenomena of spin waves, including beats in the timedomain waveform, components of integer harmonic frequencies, widerange scatterings of interharmonic frequencies, and frequency doubling in spin precession. These characteristics probably originate from various device effects: FPTs effectively excite dipolar spin waves with largeangle precession, propagating spin waves reflect from the film boundaries, and spin waves dynamically and nonlinearly interfere with each other. This study demonstrated that FPTs have promising features for both their applications to reservoir computing and the studies on the physics of nonlinear and spacevarying spin waves.
Journal of Applied Physics, Volume 132, Issue 12, September 2022. <br/>We have proposed a spinwave transducer structure named filmpenetrating transducers (FPTs). FPTs penetrate an onchip magnetic film for a spinwave transmission medium and allow flexible spatial arrangements of many exciters/detectors due to their zerodimensional feature. We constructed four device models with different spatial arrangements of FPT/conventional exciters using a 10nmthick ferrimagnetic garnet film with a central FPT detector. We performed numerical experiments that combine electromagnetics with micromagnetics including thermal noise at 300 K. We evaluated important device features of FPTs, such as the signaltonoise ratios (SNRs), input/output signal transmission efficiencies, and nonlinear phenomena of spin waves. We applied inphase sinusoidal input currents with various amplitudes and frequencies and altered the damping strengths near the film boundaries. We obtained sufficient SNRs for the practical use of FPTs and revealed that FPTs have both higher transmission efficiencies and nonlinear strengths than conventional antennas, as the input frequency approaches the ferromagnetic resonance frequency of the film. Moreover, we observed and analyzed various nonlinear phenomena of spin waves, including beats in the timedomain waveform, components of integer harmonic frequencies, widerange scatterings of interharmonic frequencies, and frequency doubling in spin precession. These characteristics probably originate from various device effects: FPTs effectively excite dipolar spin waves with largeangle precession, propagating spin waves reflect from the film boundaries, and spin waves dynamically and nonlinearly interfere with each other. This study demonstrated that FPTs have promising features for both their applications to reservoir computing and the studies on the physics of nonlinear and spacevarying spin waves.
Filmpenetrating transducers applicable to onchip reservoir computing with spin waves
10.1063/5.0102974
Journal of Applied Physics
20220922T09:49:30Z
© 2022 Author(s).
Jiaxuan Chen
Ryosho Nakane
Gouhei Tanaka
Akira Hirose

Robust bulk superconductivity by giant proximity effect in Weyl semimetalsuperconducting NbP/NbSe2 composites
https://aip.scitation.org/doi/10.1063/5.0101430?af=R&feed=mostrecent
Journal of Applied Physics, <a href="https://aip.scitation.org/toc/jap/132/12">Volume 132, Issue 12</a>, September 2022. <br/>We synthesize the Weyl semimetal/superconductor NbP/NbSe2 composite and observe stable bulk superconductivity at Tc = 7.2, 6.9, and 6.8 K for the NbSe2 crystal, NbP/NbSe2 (1:1), and NbP/NbSe2 (2:1) composites, respectively, despite large volume fraction of the nonsuperconducting NbP phase. From the Ginzburg–Landau theory, Hc2(0) is significantly enhanced in NbP/NbSe2 composites [22 T (1:1) and 18.5 T (2:1)] comparing with the pristine NbSe2 crystal (8 T). The bulk superconductivity in the Weyl semimetal/superconductor composite cannot be simply described by the de Gennes–Meissner theory in a proximity effect. From the electrical transport, magnetization, and heat capacity measurement, we obtain various superconducting parameters. The superconducting properties indicate that the NbP/NbSe2 composite is far from the conventional Bardeen–Cooper–Schrieffer superconductivity. It suggests that the Weyl semimetal/superconductor composite can have a giant proximity effect, resulting in the stable bulk superconductivity in a composite with a sizable volume fraction of nonsuperconducting Weyl semimetals. The giant proximity effect in the Weyl semimetal/superconductor interface can have a platform to investigate the proximity induced Weyl semimetallic superconducting states.
Journal of Applied Physics, Volume 132, Issue 12, September 2022. <br/>We synthesize the Weyl semimetal/superconductor NbP/NbSe2 composite and observe stable bulk superconductivity at Tc = 7.2, 6.9, and 6.8 K for the NbSe2 crystal, NbP/NbSe2 (1:1), and NbP/NbSe2 (2:1) composites, respectively, despite large volume fraction of the nonsuperconducting NbP phase. From the Ginzburg–Landau theory, Hc2(0) is significantly enhanced in NbP/NbSe2 composites [22 T (1:1) and 18.5 T (2:1)] comparing with the pristine NbSe2 crystal (8 T). The bulk superconductivity in the Weyl semimetal/superconductor composite cannot be simply described by the de Gennes–Meissner theory in a proximity effect. From the electrical transport, magnetization, and heat capacity measurement, we obtain various superconducting parameters. The superconducting properties indicate that the NbP/NbSe2 composite is far from the conventional Bardeen–Cooper–Schrieffer superconductivity. It suggests that the Weyl semimetal/superconductor composite can have a giant proximity effect, resulting in the stable bulk superconductivity in a composite with a sizable volume fraction of nonsuperconducting Weyl semimetals. The giant proximity effect in the Weyl semimetal/superconductor interface can have a platform to investigate the proximity induced Weyl semimetallic superconducting states.
Robust bulk superconductivity by giant proximity effect in Weyl semimetalsuperconducting NbP/NbSe2 composites
10.1063/5.0101430
Journal of Applied Physics
20220922T09:49:32Z
© 2022 Author(s).
Yejin Lee
Omkaram Inturu
Jin Hee Kim
JongSoo Rhyee

Pore formation in MoS2 monolayer under irradiation by swift heavy ions: A molecular dynamics study
https://aip.scitation.org/doi/10.1063/5.0108339?af=R&feed=mostrecent
Journal of Applied Physics, <a href="https://aip.scitation.org/toc/jap/132/12">Volume 132, Issue 12</a>, September 2022. <br/>Molecular dynamics simulations were performed to study the formation process of nanopores in a freestanding [math] monolayer irradiated using swift heavy ions. We considered five types of ions (Ar, Kr, Xe, W, and Bi) with energies ranging from 26 MeV to 4.5 GeV. The impact point was always located in the center of the cell far from the border to reduce undesired high energy interactions over the periodic boundaries. The twotemperature atomistic model with an explicit account of electron thermal conductivity was used. The possibility of forming pores of various shapes with sizes from 1.5 to 48 nm was found. Pore size increases with ion incident energy and decreases with ion mass. Most of the pores have internal amorphization, which can disappear with increasing the irradiation dose. Our results demonstrate that it is feasible to fabricate controlled nanopores in an [math] monolayer via swift heavy ion irradiation with Bi ions being the most efficient. Possible practical applications of the obtained results are discussed.
Journal of Applied Physics, Volume 132, Issue 12, September 2022. <br/>Molecular dynamics simulations were performed to study the formation process of nanopores in a freestanding [math] monolayer irradiated using swift heavy ions. We considered five types of ions (Ar, Kr, Xe, W, and Bi) with energies ranging from 26 MeV to 4.5 GeV. The impact point was always located in the center of the cell far from the border to reduce undesired high energy interactions over the periodic boundaries. The twotemperature atomistic model with an explicit account of electron thermal conductivity was used. The possibility of forming pores of various shapes with sizes from 1.5 to 48 nm was found. Pore size increases with ion incident energy and decreases with ion mass. Most of the pores have internal amorphization, which can disappear with increasing the irradiation dose. Our results demonstrate that it is feasible to fabricate controlled nanopores in an [math] monolayer via swift heavy ion irradiation with Bi ions being the most efficient. Possible practical applications of the obtained results are discussed.
Pore formation in MoS2 monolayer under irradiation by swift heavy ions: A molecular dynamics study
10.1063/5.0108339
Journal of Applied Physics
20220922T09:53:00Z
© 2022 Author(s).
A. Kolesnikova
V. Osipov

Chemical bonding between thorium and novel BN nanomaterials
https://aip.scitation.org/doi/10.1063/5.0102419?af=R&feed=mostrecent
Journal of Applied Physics, <a href="https://aip.scitation.org/toc/jap/132/12">Volume 132, Issue 12</a>, September 2022. <br/>We study the nature of chemical bonding of the thorium atom with novel BNbased nanomaterials: fullerenes B[math]N[math], B[math]N[math], B[math]N[math], and the BN analog of coronene—B[math]N[math]H[math], used as a representative molecular fragment of the two dimensional hexagonal BNsheet. Our ab initio calculations are performed within the dispersioncorrected density functional approach with a hybrid exchangecorrelation potential. The smallest 20atom BNfullerenes B[math]N[math], B[math]N[math] proposed by us are shown to be stable and should be observable experimentally. Thorium is found at the center of these structures pushing the outer shell of atoms farther away. The shape of the B[math]N[math]cage in Th@B[math]N[math] is conserved, while the shape of the B[math]N[math] molecule in Th@B[math]N[math] is largely deformed. The initially planar structure of B[math]N[math]H[math] in the presence of thorium becomes corrugated, demonstrating pronounced offplane displacements under the thorium atom. Other fourvalent metals (Ti, Zr, and Hf) also cause offplane displacements of B and N atoms albeit to a much smaller scale. In the 60atom fullerene B[math]N[math], which is the BN analog of C[math], two conformations of Th@B[math]N[math] are found: one is with thorium facing the hexagon with one B–B and one N–N covalent bonds and a second, lying 0.79 eV higher, with thorium close to the center of pentagon with one B–B covalent bond.
Journal of Applied Physics, Volume 132, Issue 12, September 2022. <br/>We study the nature of chemical bonding of the thorium atom with novel BNbased nanomaterials: fullerenes B[math]N[math], B[math]N[math], B[math]N[math], and the BN analog of coronene—B[math]N[math]H[math], used as a representative molecular fragment of the two dimensional hexagonal BNsheet. Our ab initio calculations are performed within the dispersioncorrected density functional approach with a hybrid exchangecorrelation potential. The smallest 20atom BNfullerenes B[math]N[math], B[math]N[math] proposed by us are shown to be stable and should be observable experimentally. Thorium is found at the center of these structures pushing the outer shell of atoms farther away. The shape of the B[math]N[math]cage in Th@B[math]N[math] is conserved, while the shape of the B[math]N[math] molecule in Th@B[math]N[math] is largely deformed. The initially planar structure of B[math]N[math]H[math] in the presence of thorium becomes corrugated, demonstrating pronounced offplane displacements under the thorium atom. Other fourvalent metals (Ti, Zr, and Hf) also cause offplane displacements of B and N atoms albeit to a much smaller scale. In the 60atom fullerene B[math]N[math], which is the BN analog of C[math], two conformations of Th@B[math]N[math] are found: one is with thorium facing the hexagon with one B–B and one N–N covalent bonds and a second, lying 0.79 eV higher, with thorium close to the center of pentagon with one B–B covalent bond.
Chemical bonding between thorium and novel BN nanomaterials
10.1063/5.0102419
Journal of Applied Physics
20220923T09:51:36Z
© 2022 Author(s).
U. N. Kurelchuk
A. V. Nikolaev
P. V. Borisyuk
E. V. Tkalya

An exact tunneling model and its application to transmission and reflection delay times
https://aip.scitation.org/doi/10.1063/5.0096568?af=R&feed=mostrecent
Journal of Applied Physics, <a href="https://aip.scitation.org/toc/jap/132/12">Volume 132, Issue 12</a>, September 2022. <br/>Electron emission into a nanogap is not instantaneous, which presents a difficulty in simulating ultrafast behavior using particle models. A method of approximating the transmission and reflection delay (TARD) times of a wave packet interacting with barriers described by a delta function, a metal–insulator–metal (MIM, rectangular) barrier, and a Fowler Nordheim (FN, triangular) barrier is given and has application to simulation. It is based on the superposition of a finite number of exact basis states obtained from Schrödinger’s equation, analogous to how quantum carpets are simulated. As a result, it can exactly and uniquely follow exponentially small tunneling currents. A Bohmlike trajectory is obtained from the time evolution of the density: it shows delay in both the transmitted and reflected packets that can be simply evaluated. The relations to prior studies of the analytic [math]function barrier and the Wigner distribution function (WDF) methods are described. A comparison of the TARD times is contrasted to alternate times in the Büttiker–Landauer (BL) and McColl–Hartman (MH) times; the MH approach is further reformulated explicitly in terms of Gamow factors to consider how the McColl–Hartman effect is to be related, particularly in the case of the FN barrier of field emission.
Journal of Applied Physics, Volume 132, Issue 12, September 2022. <br/>Electron emission into a nanogap is not instantaneous, which presents a difficulty in simulating ultrafast behavior using particle models. A method of approximating the transmission and reflection delay (TARD) times of a wave packet interacting with barriers described by a delta function, a metal–insulator–metal (MIM, rectangular) barrier, and a Fowler Nordheim (FN, triangular) barrier is given and has application to simulation. It is based on the superposition of a finite number of exact basis states obtained from Schrödinger’s equation, analogous to how quantum carpets are simulated. As a result, it can exactly and uniquely follow exponentially small tunneling currents. A Bohmlike trajectory is obtained from the time evolution of the density: it shows delay in both the transmitted and reflected packets that can be simply evaluated. The relations to prior studies of the analytic [math]function barrier and the Wigner distribution function (WDF) methods are described. A comparison of the TARD times is contrasted to alternate times in the Büttiker–Landauer (BL) and McColl–Hartman (MH) times; the MH approach is further reformulated explicitly in terms of Gamow factors to consider how the McColl–Hartman effect is to be related, particularly in the case of the FN barrier of field emission.
An exact tunneling model and its application to transmission and reflection delay times
10.1063/5.0096568
Journal of Applied Physics
20220927T11:34:59Z
Kevin L. Jensen
Jeanne Riga
Joel L. Lebowitz
Rebecca Seviour
Donald A. Shiffler

Phasefield model of grain boundary diffusion in nanocrystalline solids: Anisotropic fluctuations, anomalous diffusion, and precipitation
https://aip.scitation.org/doi/10.1063/5.0101489?af=R&feed=mostrecent
Journal of Applied Physics, <a href="https://aip.scitation.org/toc/jap/132/12">Volume 132, Issue 12</a>, September 2022. <br/>The anisotropic phasefiled model of grain boundary diffusion and precipitation of solute in nanocrystalline solids has been developed. In this model, the Cahn–Hilliard equation is generalized for the anisotropic phasefield diffusion of solute and anisotropic compositional fluctuations. It is found that dynamics of solute concentration profile demonstrates the anomalous diffusion behavior with scaling parameters depending on the mobility ratio and microstructure of a solid solution. It is noteworthy that the increase in source concentration can slow down the concentration front propagation due to uphill diffusion or formation of a new phase. Parameters of grain boundary diffusion control the precipitation dynamics. In particular, a decrease in transverse diffusion coefficient is responsible for longer incubation time, and lower rates of nucleation and nuclei growth in comparison with the case of isotropic solute transport near grain boundaries. Transport properties of boundary and bulk are responsible for the formation of the bimodal size distribution function of second phase particles and specific kinetics of average radius and number density.
Journal of Applied Physics, Volume 132, Issue 12, September 2022. <br/>The anisotropic phasefiled model of grain boundary diffusion and precipitation of solute in nanocrystalline solids has been developed. In this model, the Cahn–Hilliard equation is generalized for the anisotropic phasefield diffusion of solute and anisotropic compositional fluctuations. It is found that dynamics of solute concentration profile demonstrates the anomalous diffusion behavior with scaling parameters depending on the mobility ratio and microstructure of a solid solution. It is noteworthy that the increase in source concentration can slow down the concentration front propagation due to uphill diffusion or formation of a new phase. Parameters of grain boundary diffusion control the precipitation dynamics. In particular, a decrease in transverse diffusion coefficient is responsible for longer incubation time, and lower rates of nucleation and nuclei growth in comparison with the case of isotropic solute transport near grain boundaries. Transport properties of boundary and bulk are responsible for the formation of the bimodal size distribution function of second phase particles and specific kinetics of average radius and number density.
Phasefield model of grain boundary diffusion in nanocrystalline solids: Anisotropic fluctuations, anomalous diffusion, and precipitation
10.1063/5.0101489
Journal of Applied Physics
20220927T11:34:58Z
© 2022 Author(s).
Pavel E. L’vov
Renat T. Sibatov

The theory for a 2D electron diffractometer using graphene
https://aip.scitation.org/doi/10.1063/5.0104971?af=R&feed=mostrecent
Journal of Applied Physics, <a href="https://aip.scitation.org/toc/jap/132/12">Volume 132, Issue 12</a>, September 2022. <br/>Electrons near the Fermi level behaving as massless Dirac fermions in graphene in (1+2)D relativistic spacetime have been confirmed by an experiment. Using this aspect, a myriad of novel and interesting devices can be sought. In this paper, we laid out the theory for using a monolayer graphene sheet as an electron diffractometer, aiming at the determination of surface properties in materials. The key ingredient is the Mott scattering of electrons by screened Coulomb scatterers in (1+2)D spacetime. The specific array of scatterers provided by a given surface placed in contact with a graphene sheet will induce an angular distribution for the electron scattering events, which can be properly measured through the electric current flowing to external electrodes. It can provide an in situ technique for characterizing quantum dot superlattices with a resolution of a few nanometers.
Journal of Applied Physics, Volume 132, Issue 12, September 2022. <br/>Electrons near the Fermi level behaving as massless Dirac fermions in graphene in (1+2)D relativistic spacetime have been confirmed by an experiment. Using this aspect, a myriad of novel and interesting devices can be sought. In this paper, we laid out the theory for using a monolayer graphene sheet as an electron diffractometer, aiming at the determination of surface properties in materials. The key ingredient is the Mott scattering of electrons by screened Coulomb scatterers in (1+2)D spacetime. The specific array of scatterers provided by a given surface placed in contact with a graphene sheet will induce an angular distribution for the electron scattering events, which can be properly measured through the electric current flowing to external electrodes. It can provide an in situ technique for characterizing quantum dot superlattices with a resolution of a few nanometers.
The theory for a 2D electron diffractometer using graphene
10.1063/5.0104971
Journal of Applied Physics
20220928T11:37:18Z
© 2022 Author(s).
C. A. Dartora
Fernando Zanella
G. G. Cabrera

Single atom precise, ultrafast, and universal emulation of biological synapses using atomically thin vertical heterostructures
https://aip.scitation.org/doi/10.1063/5.0112920?af=R&feed=mostrecent
Journal of Applied Physics, <a href="https://aip.scitation.org/toc/jap/132/12">Volume 132, Issue 12</a>, September 2022. <br/>We propose three vertical heterostructures of twodimensional materials composed of MoS[math] and AlN single layers to emulate biological synaptic behaviors. We aim to show a socalled healthy synaptic behavior with an N vacancydefected heterostructure, dysfunctional synaptic behavior with a pristine heterostructure, and repaired synaptic behaviors using an N intercalated heterostructure. We compare the abilities of those proposed artificial synapses using density functional theory, Boltzmann transport methods, and realtime time dependent density functional theory. We find that the vacancydefected heterostructure can mimic the biological synaptic behaviors better than the others. We conclude a relation between learning abilities and synaptic abilities. A combination of logic and memory abilities is positively correlated with synaptic abilities. These results are significant to emulate the brain on a large scale, with ultrathin and low power consumption heterostructures.
Journal of Applied Physics, Volume 132, Issue 12, September 2022. <br/>We propose three vertical heterostructures of twodimensional materials composed of MoS[math] and AlN single layers to emulate biological synaptic behaviors. We aim to show a socalled healthy synaptic behavior with an N vacancydefected heterostructure, dysfunctional synaptic behavior with a pristine heterostructure, and repaired synaptic behaviors using an N intercalated heterostructure. We compare the abilities of those proposed artificial synapses using density functional theory, Boltzmann transport methods, and realtime time dependent density functional theory. We find that the vacancydefected heterostructure can mimic the biological synaptic behaviors better than the others. We conclude a relation between learning abilities and synaptic abilities. A combination of logic and memory abilities is positively correlated with synaptic abilities. These results are significant to emulate the brain on a large scale, with ultrathin and low power consumption heterostructures.
Single atom precise, ultrafast, and universal emulation of biological synapses using atomically thin vertical heterostructures
10.1063/5.0112920
Journal of Applied Physics
20220928T11:37:21Z
© 2022 Author(s).
Aykut Turfanda
Hilmi Ünlü

Highaccuracy determination of Paultrap stability parameters for electricquadrupoleshift prediction
https://aip.scitation.org/doi/10.1063/5.0106633?af=R&feed=mostrecent
Journal of Applied Physics, <a href="https://aip.scitation.org/toc/jap/132/12">Volume 132, Issue 12</a>, September 2022. <br/>The motion of an ion in a radiofrequency (rf) Paul trap is described by the Mathieu equation and the associated stability parameters that are proportional to the rf and dc electric field gradients. Here, a higherorder, iterative method to accurately solve the stability parameters from measured secular frequencies is presented. It is then used to characterize an endcap trap by showing that the trap’s radial asymmetry is dominated by the dc field gradients and by measuring the relation between the applied voltages and the gradients. The results are shown to be in good agreement with an electrostatic finiteelementmethod simulation of the trap. Furthermore, a method to determine the direction of the radial trap axes using a “tickler” voltage is presented, and the temperature dependence of the rf voltage is discussed. As an application for optical ion clocks, the method is used to predict and minimize the electric quadrupole shift (EQS) using the applied dc voltages. Finally, a lower limit of 1070 for the cancellation factor of the Zeemanaveraging EQS cancellation method is determined in an interleaved low/highEQS clock measurement. This reduces the EQS uncertainty of our [math]Sr[math] optical clock to [math] in fractional frequency units.
Journal of Applied Physics, Volume 132, Issue 12, September 2022. <br/>The motion of an ion in a radiofrequency (rf) Paul trap is described by the Mathieu equation and the associated stability parameters that are proportional to the rf and dc electric field gradients. Here, a higherorder, iterative method to accurately solve the stability parameters from measured secular frequencies is presented. It is then used to characterize an endcap trap by showing that the trap’s radial asymmetry is dominated by the dc field gradients and by measuring the relation between the applied voltages and the gradients. The results are shown to be in good agreement with an electrostatic finiteelementmethod simulation of the trap. Furthermore, a method to determine the direction of the radial trap axes using a “tickler” voltage is presented, and the temperature dependence of the rf voltage is discussed. As an application for optical ion clocks, the method is used to predict and minimize the electric quadrupole shift (EQS) using the applied dc voltages. Finally, a lower limit of 1070 for the cancellation factor of the Zeemanaveraging EQS cancellation method is determined in an interleaved low/highEQS clock measurement. This reduces the EQS uncertainty of our [math]Sr[math] optical clock to [math] in fractional frequency units.
Highaccuracy determination of Paultrap stability parameters for electricquadrupoleshift prediction
10.1063/5.0106633
Journal of Applied Physics
20220927T11:34:56Z
© 2022 Author(s).
T. Lindvall
K. J. Hanhijärvi
T. Fordell
A. E. Wallin

The influence of edge waves in local surface skimming longitudinal wave generation using a focused PVDF transducer
https://aip.scitation.org/doi/10.1063/5.0100161?af=R&feed=mostrecent
Journal of Applied Physics, <a href="https://aip.scitation.org/toc/jap/132/12">Volume 132, Issue 12</a>, September 2022. <br/>Acoustic microscopy is extensively used for highfrequency imaging and material characterization. In a focused ultrasonic transducer, the presence of edge waves from the edge of the transducer is usually considered a disadvantage. For highfrequency imaging applications, the edge waves adversely affect the quality of the image. This paper discusses edge wave's influence on generating a surface wave in bulk metal samples using a limited aperture PVDF transducer. Acoustic microscopybased defocusing experiments are conducted on aluminum, stainless steel, copper, and brass samples. A detailed wavepath analysis is done to understand the different wave components in a signal as obtained from defocusing experiments. The travel path of each wave component is analytically obtained and compared with the experimental results. The different wave modes observed in the experiments are identified by overlaying the analytical plots on the experimentally obtained Bscans. A good correlation is obtained between the experimental and analytical results. The surface wave velocity of the samples is calculated using the timeresolved method, and the percentage of error in the measurement is estimated. The challenges for using this method in measuring surface wave velocities in samples with bulk longitudinal velocities [math] are also discussed.
Journal of Applied Physics, Volume 132, Issue 12, September 2022. <br/>Acoustic microscopy is extensively used for highfrequency imaging and material characterization. In a focused ultrasonic transducer, the presence of edge waves from the edge of the transducer is usually considered a disadvantage. For highfrequency imaging applications, the edge waves adversely affect the quality of the image. This paper discusses edge wave's influence on generating a surface wave in bulk metal samples using a limited aperture PVDF transducer. Acoustic microscopybased defocusing experiments are conducted on aluminum, stainless steel, copper, and brass samples. A detailed wavepath analysis is done to understand the different wave components in a signal as obtained from defocusing experiments. The travel path of each wave component is analytically obtained and compared with the experimental results. The different wave modes observed in the experiments are identified by overlaying the analytical plots on the experimentally obtained Bscans. A good correlation is obtained between the experimental and analytical results. The surface wave velocity of the samples is calculated using the timeresolved method, and the percentage of error in the measurement is estimated. The challenges for using this method in measuring surface wave velocities in samples with bulk longitudinal velocities [math] are also discussed.
The influence of edge waves in local surface skimming longitudinal wave generation using a focused PVDF transducer
10.1063/5.0100161
Journal of Applied Physics
20220927T11:35:02Z
© 2022 Author(s).
Anoop Upendran
Krishnan Balasubramanian

Mode couplings in multiplex electromechanical structures
https://aip.scitation.org/doi/10.1063/5.0103146?af=R&feed=mostrecent
Journal of Applied Physics, <a href="https://aip.scitation.org/toc/jap/132/12">Volume 132, Issue 12</a>, September 2022. <br/>Mode couplings associated with elastic wave propagation through threedimensional multiplex structures, as manifested by asymmetric eigenmodes and dissipation, determine the efficiency of electromechanical structures. As a result, it is critical to predict electroelastic symmetric modes such as thickness expander and radial modes, as well as asymmetric flexural modes, while accounting for material losses. Multiplex electromechanical structures include multilayered throughwall ultrasound power transfer (TWUPT) systems. Physical processes that support TWUPT include vibrations at a transmitting/acoustic source element, elastic wave propagation through a barrier and coupling layers, piezoelectric transduction of elastic vibrations at a receiving element, and spatial resonances of the transmitting and receiving elements. We investigate mode couplings in an optimized modal TWUPT system, including their physical origins, models used to describe them, and regimes of weak and strong couplings. The system layout optimization is defined in terms of size (volume), operating frequency, and matching circuit load optimization. A computational model is developed and utilized in conjunction with experimental modal characterization to highlight the impact of eigenmode features on optimization results. Several behavioral modes are identified and analyzed. The interaction of symmetric radial and asymmetric flexural modes causes the system damping to increase and the device's overall efficiency to decrease. The electromechanical coupling factor value is likewise reduced as a result of this. Such occurrences are explained by the flow of energy between modes as they interact. The present work also proposes design guidelines to improve the performance of TWUPT systems based on exploiting inherent physical phenomena.
Journal of Applied Physics, Volume 132, Issue 12, September 2022. <br/>Mode couplings associated with elastic wave propagation through threedimensional multiplex structures, as manifested by asymmetric eigenmodes and dissipation, determine the efficiency of electromechanical structures. As a result, it is critical to predict electroelastic symmetric modes such as thickness expander and radial modes, as well as asymmetric flexural modes, while accounting for material losses. Multiplex electromechanical structures include multilayered throughwall ultrasound power transfer (TWUPT) systems. Physical processes that support TWUPT include vibrations at a transmitting/acoustic source element, elastic wave propagation through a barrier and coupling layers, piezoelectric transduction of elastic vibrations at a receiving element, and spatial resonances of the transmitting and receiving elements. We investigate mode couplings in an optimized modal TWUPT system, including their physical origins, models used to describe them, and regimes of weak and strong couplings. The system layout optimization is defined in terms of size (volume), operating frequency, and matching circuit load optimization. A computational model is developed and utilized in conjunction with experimental modal characterization to highlight the impact of eigenmode features on optimization results. Several behavioral modes are identified and analyzed. The interaction of symmetric radial and asymmetric flexural modes causes the system damping to increase and the device's overall efficiency to decrease. The electromechanical coupling factor value is likewise reduced as a result of this. Such occurrences are explained by the flow of energy between modes as they interact. The present work also proposes design guidelines to improve the performance of TWUPT systems based on exploiting inherent physical phenomena.
Mode couplings in multiplex electromechanical structures
10.1063/5.0103146
Journal of Applied Physics
20220930T09:46:19Z
© 2022 Author(s).
Moustafa Sayed Ahmed
Mehdi Ghommem
Shima Shahab

Effect of atomic types and concentration on the mechanical properties of CoNibased concentrated solidsolution alloys
https://aip.scitation.org/doi/10.1063/5.0102785?af=R&feed=mostrecent
Journal of Applied Physics, <a href="https://aip.scitation.org/toc/jap/132/12">Volume 132, Issue 12</a>, September 2022. <br/>Concentrated solidsolution alloys (CSAs) are a new type of alloy material with high strength, extreme hardness, remarkable corrosion resistance, and excellent radiation resistance. The mechanical properties of CSAs are strongly determined by the types and concentration of component elements, which provide a large space for design. In this work, molecular dynamics simulations were implemented to investigate the mechanical properties of CoNibased CSAs. Our study showed that there is a significant effect of constituent types on the yield stress and Young's modulus of CoNibased CSAs. The yield stress and Young's modulus of CoNiFeAlCu CSAs with equal atomic ratios were found to be 3.02 and 70.94 GPa, respectively. With the increase in the Fe concentration, the yield stress and Young's modulus of the CSAs decrease gradually; on the contrary, these properties increase gradually with an increase in the Al concentration. The CoNiFeCuAl6 CSA was found to exhibit high strength and good plastic deformation ability, which originates from the significant increase in the dislocation density. Hence, the large design space of CSAs presents a great opportunity to select CSAs with excellent mechanical properties for structural applications.
Journal of Applied Physics, Volume 132, Issue 12, September 2022. <br/>Concentrated solidsolution alloys (CSAs) are a new type of alloy material with high strength, extreme hardness, remarkable corrosion resistance, and excellent radiation resistance. The mechanical properties of CSAs are strongly determined by the types and concentration of component elements, which provide a large space for design. In this work, molecular dynamics simulations were implemented to investigate the mechanical properties of CoNibased CSAs. Our study showed that there is a significant effect of constituent types on the yield stress and Young's modulus of CoNibased CSAs. The yield stress and Young's modulus of CoNiFeAlCu CSAs with equal atomic ratios were found to be 3.02 and 70.94 GPa, respectively. With the increase in the Fe concentration, the yield stress and Young's modulus of the CSAs decrease gradually; on the contrary, these properties increase gradually with an increase in the Al concentration. The CoNiFeCuAl6 CSA was found to exhibit high strength and good plastic deformation ability, which originates from the significant increase in the dislocation density. Hence, the large design space of CSAs presents a great opportunity to select CSAs with excellent mechanical properties for structural applications.
Effect of atomic types and concentration on the mechanical properties of CoNibased concentrated solidsolution alloys
10.1063/5.0102785
Journal of Applied Physics
20220922T09:53:01Z
© 2022 Author(s).
Chao Zhang
Xinxin Wang
Shuai Chen
YongWei Zhang

Hydrophilic porous materials as helmet padding able to prevent traumatic brain injuries
https://aip.scitation.org/doi/10.1063/5.0114107?af=R&feed=mostrecent
Journal of Applied Physics, <a href="https://aip.scitation.org/toc/jap/132/12">Volume 132, Issue 12</a>, September 2022. <br/>The ideal way to reduce the likelihood of traumatic brain injuries for a player engaged in an impact sport such as football or hockey, as a result of an impact of his/her helmet with a surface or another player, would be to reduce the average value of the acceleration of the player's head in an impact as much as possible. The minimum possible value of the average deceleration of the head is inversely proportional to the helmet padding thickness. Since there are practical limits to its maximum thickness, it is difficult to significantly reduce the average acceleration. There is evidence, however, that the peak, rather than the average, acceleration is the most significant cause of brain injury. It is proposed here that brain injuries, that occur as a result of an impact, could be reduced by using as padding a hydrophilic porous material swollen with fluid. The friction experienced by the fluid as it is squeezed out of the porous material in an impact can “tune” the acceleration of the skull so that it is never significantly higher than its average value during the impact.
Journal of Applied Physics, Volume 132, Issue 12, September 2022. <br/>The ideal way to reduce the likelihood of traumatic brain injuries for a player engaged in an impact sport such as football or hockey, as a result of an impact of his/her helmet with a surface or another player, would be to reduce the average value of the acceleration of the player's head in an impact as much as possible. The minimum possible value of the average deceleration of the head is inversely proportional to the helmet padding thickness. Since there are practical limits to its maximum thickness, it is difficult to significantly reduce the average acceleration. There is evidence, however, that the peak, rather than the average, acceleration is the most significant cause of brain injury. It is proposed here that brain injuries, that occur as a result of an impact, could be reduced by using as padding a hydrophilic porous material swollen with fluid. The friction experienced by the fluid as it is squeezed out of the porous material in an impact can “tune” the acceleration of the skull so that it is never significantly higher than its average value during the impact.
Hydrophilic porous materials as helmet padding able to prevent traumatic brain injuries
10.1063/5.0114107
Journal of Applied Physics
20220922T09:55:00Z
© 2022 Author(s).
J. B. Sokoloff

A scattering matrix formalism to model periodic heat diffusion in stratified solid media
https://aip.scitation.org/doi/10.1063/5.0111267?af=R&feed=mostrecent
Journal of Applied Physics, <a href="https://aip.scitation.org/toc/jap/132/12">Volume 132, Issue 12</a>, September 2022. <br/>Transfer matrix formalism is widely used in modeling periodic heat diffusion in layered structures. Due to an intrinsic numerical instability issue, this formalism fails at high heating frequencies and/or in thick structures. Inspired by its success in modeling wave propagation, we develop a numerically stable scattering matrix framework to model periodic heat diffusion in stratified solid media. As a concrete example, we apply this scattering matrix methodology to the 3ω method. We first validate our framework using various wellknown solutions. Next, we demonstrate the numerical stability of the framework using a configuration that resembles the threedimensional stacked architecture for chip packing. Last, we propose synthetic “experiments” to exhibit, under certain circumstances, the merits of the scattering matrix formalism in extracting thermal properties.
Journal of Applied Physics, Volume 132, Issue 12, September 2022. <br/>Transfer matrix formalism is widely used in modeling periodic heat diffusion in layered structures. Due to an intrinsic numerical instability issue, this formalism fails at high heating frequencies and/or in thick structures. Inspired by its success in modeling wave propagation, we develop a numerically stable scattering matrix framework to model periodic heat diffusion in stratified solid media. As a concrete example, we apply this scattering matrix methodology to the 3ω method. We first validate our framework using various wellknown solutions. Next, we demonstrate the numerical stability of the framework using a configuration that resembles the threedimensional stacked architecture for chip packing. Last, we propose synthetic “experiments” to exhibit, under certain circumstances, the merits of the scattering matrix formalism in extracting thermal properties.
A scattering matrix formalism to model periodic heat diffusion in stratified solid media
10.1063/5.0111267
Journal of Applied Physics
20220922T09:55:01Z
© 2022 Author(s).
Tao Li
Zhen Chen

Discovery of a new criterion for predicting glassforming ability based on symbolic regression and artificial neural network
https://aip.scitation.org/doi/10.1063/5.0105445?af=R&feed=mostrecent
Journal of Applied Physics, <a href="https://aip.scitation.org/toc/jap/132/12">Volume 132, Issue 12</a>, September 2022. <br/>Metallic glasses (MGs) are widely used in various fields due to their superior physical properties. Glassforming ability (GFA) represents the difficulty of forming MGs. Therefore, understanding and establishing the connection between materials characteristics and GFA is a great challenge in MGs research. In this work, to generate a new criterion to characterize GFA, symbolic regression and artificial neural network (ANN) were employed built on 7795 pieces of data. A completely new criterion was proposed and revealed the relationship between three characteristic temperatures (wherein Tg is the glass transition temperature, Tx is the onset crystallization temperature, and Tl is the liquidus temperature) and GFA. The new criterion not only exhibits a higher correlation to the critical casting diameter (Dmax) than the other 11 reported criteria but also illustrates the importance of high power (Tx − Tg)/(Tl − Tx) in characterizing GFA. Moreover, to test the criterion on unreported data, three models that can, respectively, perform GFA classification, predict Dmax, and three characteristic temperatures were built through artificial neural networks. Then, 439 new data generated by the ANN model were generated by models applied on Zr–Co–Al–X (X = W, Si, and Ni) alloys. On the testing data, the new criterion shows stronger generalization than other criteria, which proves its reliability and effectiveness.
Journal of Applied Physics, Volume 132, Issue 12, September 2022. <br/>Metallic glasses (MGs) are widely used in various fields due to their superior physical properties. Glassforming ability (GFA) represents the difficulty of forming MGs. Therefore, understanding and establishing the connection between materials characteristics and GFA is a great challenge in MGs research. In this work, to generate a new criterion to characterize GFA, symbolic regression and artificial neural network (ANN) were employed built on 7795 pieces of data. A completely new criterion was proposed and revealed the relationship between three characteristic temperatures (wherein Tg is the glass transition temperature, Tx is the onset crystallization temperature, and Tl is the liquidus temperature) and GFA. The new criterion not only exhibits a higher correlation to the critical casting diameter (Dmax) than the other 11 reported criteria but also illustrates the importance of high power (Tx − Tg)/(Tl − Tx) in characterizing GFA. Moreover, to test the criterion on unreported data, three models that can, respectively, perform GFA classification, predict Dmax, and three characteristic temperatures were built through artificial neural networks. Then, 439 new data generated by the ANN model were generated by models applied on Zr–Co–Al–X (X = W, Si, and Ni) alloys. On the testing data, the new criterion shows stronger generalization than other criteria, which proves its reliability and effectiveness.
Discovery of a new criterion for predicting glassforming ability based on symbolic regression and artificial neural network
10.1063/5.0105445
Journal of Applied Physics
20220923T09:51:46Z
© 2022 Author(s).
Baofeng Tan
YongChao Liang
Qian Chen
Li Zhang
JiaJun Ma

Random 2D nanowire networks: Finitesize effect and the effect of busbar/nanowire contact resistance on their electrical conductivity
https://aip.scitation.org/doi/10.1063/5.0110523?af=R&feed=mostrecent
Journal of Applied Physics, <a href="https://aip.scitation.org/toc/jap/132/12">Volume 132, Issue 12</a>, September 2022. <br/>We have studied the resistance of twodimensional random percolating networks of zerowidth metallic nanowires (rings or sticks). We took into account the nanowire resistance per unit length, the junction (nanowire/nanowire contact) resistance, and the busbar/nanowire contact resistance. Using a meanfield approximation (MFA), we derived the total resistance of the nanoringbased networks as a function of their geometrical and physical parameters. We have proposed a way of accounting for the contribution of the busbar/nanowire contact resistance toward the network resistance. The MFA predictions have been confirmed by our Monte Carlo numerical simulations. Our study evidenced that the busbar/nanowire contact resistance has a significant effect on the electrical conductivity when the junction resistance dominates over the wire resistance.
Journal of Applied Physics, Volume 132, Issue 12, September 2022. <br/>We have studied the resistance of twodimensional random percolating networks of zerowidth metallic nanowires (rings or sticks). We took into account the nanowire resistance per unit length, the junction (nanowire/nanowire contact) resistance, and the busbar/nanowire contact resistance. Using a meanfield approximation (MFA), we derived the total resistance of the nanoringbased networks as a function of their geometrical and physical parameters. We have proposed a way of accounting for the contribution of the busbar/nanowire contact resistance toward the network resistance. The MFA predictions have been confirmed by our Monte Carlo numerical simulations. Our study evidenced that the busbar/nanowire contact resistance has a significant effect on the electrical conductivity when the junction resistance dominates over the wire resistance.
Random 2D nanowire networks: Finitesize effect and the effect of busbar/nanowire contact resistance on their electrical conductivity
10.1063/5.0110523
Journal of Applied Physics
20220923T09:51:48Z
© 2022 Author(s).
Yuri Yu. Tarasevich
Andrei V. Eserkepov
Irina V. Vodolazskaya

Theoretical investigation on yttrium clustering in tungsten grain boundary region and strengthening effect
https://aip.scitation.org/doi/10.1063/5.0102744?af=R&feed=mostrecent
Journal of Applied Physics, <a href="https://aip.scitation.org/toc/jap/132/12">Volume 132, Issue 12</a>, September 2022. <br/>We have systematically investigated the solution and aggregation behaviors of yttrium (Y) on symmetrically inclined tungsten (W) grain boundary (GB) [math](310)/[001] by firstprinciples simulation. It is found that the most stable site for Y is located on the GB plane, and the solution energy of the Y substitutional site increases with increasing the distance from the GB plane. The charge redistribution of Y atoms is positively correlated with the solution energy, i.e., the deviation of the electrons of Y atoms is beneficial to its solution in the W–GB system. Further, the segregation of multiple Y atoms in the W–GB is clearly observed, where the Y atoms preferentially occupy the GB plane substitutional sites. The alloying Y atoms at the GB plane sites can effectively strengthen the GB when the concentration is less than 3.367%. The stronger binding energy of W–Y than the binding energy of W–W in the GB region is the main factor for the strengthening of the GB.
Journal of Applied Physics, Volume 132, Issue 12, September 2022. <br/>We have systematically investigated the solution and aggregation behaviors of yttrium (Y) on symmetrically inclined tungsten (W) grain boundary (GB) [math](310)/[001] by firstprinciples simulation. It is found that the most stable site for Y is located on the GB plane, and the solution energy of the Y substitutional site increases with increasing the distance from the GB plane. The charge redistribution of Y atoms is positively correlated with the solution energy, i.e., the deviation of the electrons of Y atoms is beneficial to its solution in the W–GB system. Further, the segregation of multiple Y atoms in the W–GB is clearly observed, where the Y atoms preferentially occupy the GB plane substitutional sites. The alloying Y atoms at the GB plane sites can effectively strengthen the GB when the concentration is less than 3.367%. The stronger binding energy of W–Y than the binding energy of W–W in the GB region is the main factor for the strengthening of the GB.
Theoretical investigation on yttrium clustering in tungsten grain boundary region and strengthening effect
10.1063/5.0102744
Journal of Applied Physics
20220928T11:39:19Z
© 2022 Author(s).
Mingyu Wu
Yujuan Zhang
Zhihang Wang
Kaikai Qiu
Yaxian Shi
Changchun Ge

Bending a graphene cantilever by a diamagnetic force
https://aip.scitation.org/doi/10.1063/5.0105472?af=R&feed=mostrecent
Journal of Applied Physics, <a href="https://aip.scitation.org/toc/jap/132/12">Volume 132, Issue 12</a>, September 2022. <br/>The application of a magnetic field perpendicular to the surface of a graphene cantilever generates a bending force owing to the strong anisotropy of the magnetic susceptibility. We calculate the mechanically stable equilibrium shape of a graphene cantilever in the presence of a magnetic field by minimizing the magnetic and bending energies, which are calculated using the tightbinding model and the Tersoff–Brenner potential, respectively. Furthermore, the introduction of a continuous model enables the sizedependence of the displacement by bending to be considered.
Journal of Applied Physics, Volume 132, Issue 12, September 2022. <br/>The application of a magnetic field perpendicular to the surface of a graphene cantilever generates a bending force owing to the strong anisotropy of the magnetic susceptibility. We calculate the mechanically stable equilibrium shape of a graphene cantilever in the presence of a magnetic field by minimizing the magnetic and bending energies, which are calculated using the tightbinding model and the Tersoff–Brenner potential, respectively. Furthermore, the introduction of a continuous model enables the sizedependence of the displacement by bending to be considered.
Bending a graphene cantilever by a diamagnetic force
10.1063/5.0105472
Journal of Applied Physics
20220928T11:39:20Z
© 2022 Author(s).
Norio Inui
Kazunori Maebuchi

Maximum electromomentum coupling in piezoelectric metamaterial scatterers
https://aip.scitation.org/doi/10.1063/5.0112796?af=R&feed=mostrecent
Journal of Applied Physics, <a href="https://aip.scitation.org/toc/jap/132/12">Volume 132, Issue 12</a>, September 2022. <br/>Engineered piezoelectric metamaterials can possess electromomentum coupling between the macroscopic momentum and electric stimuli. This indicates the applicability of such metamaterials for wave scattering with an extra design degree of freedom, in the same way as Willis materials. To fully utilize this novel bianisotropy, we derive for the firsttime theoretical bounds on electromomentum coupling in wave scattering via energy conservation. As this coupling acts on both elastodynamics and electromagnetics, the polarizability tensor is generalized to fill their link in the bounds. Our derived bounds are verified via analytical scattering solutions. Results show that the bianisotropic scattering can be of the same order as the nonbianisotropic terms via the aid of electromomentum coupling even for small Willis coupling. We further reveal the possibility of using electromomentum coupling for tunable cloaking. This sheds light on the promising potential of piezoelectric metamaterials for tunable scattering devices whose bianisotropy can be modulated by external electric stimuli.
Journal of Applied Physics, Volume 132, Issue 12, September 2022. <br/>Engineered piezoelectric metamaterials can possess electromomentum coupling between the macroscopic momentum and electric stimuli. This indicates the applicability of such metamaterials for wave scattering with an extra design degree of freedom, in the same way as Willis materials. To fully utilize this novel bianisotropy, we derive for the firsttime theoretical bounds on electromomentum coupling in wave scattering via energy conservation. As this coupling acts on both elastodynamics and electromagnetics, the polarizability tensor is generalized to fill their link in the bounds. Our derived bounds are verified via analytical scattering solutions. Results show that the bianisotropic scattering can be of the same order as the nonbianisotropic terms via the aid of electromomentum coupling even for small Willis coupling. We further reveal the possibility of using electromomentum coupling for tunable cloaking. This sheds light on the promising potential of piezoelectric metamaterials for tunable scattering devices whose bianisotropy can be modulated by external electric stimuli.
Maximum electromomentum coupling in piezoelectric metamaterial scatterers
10.1063/5.0112796
Journal of Applied Physics
20220928T11:39:19Z
© 2022 Author(s).
JeongHo Lee
Zhizhou Zhang
Grace X. Gu

Improved methods for design of PLD and combinatorial PLD films
https://aip.scitation.org/doi/10.1063/5.0105298?af=R&feed=mostrecent
Journal of Applied Physics, <a href="https://aip.scitation.org/toc/jap/132/12">Volume 132, Issue 12</a>, September 2022. <br/>Pulsed laser deposition (PLD) is a powerful technique for prototyping thin film materials, both single component (single composition) films and films with a varying composition (e.g., lateral continuous compositional spread, CCS). In this work, we improve one of the simulation methods used to design the deposition of PLD films: We extend the mathematical model for the material spread on the substrate, [math], for each laser pulse hitting the target, and we use a more accurate method to determine [math] experimentally. The deposition of the material on the substrate is simulated by repetitively adding [math], from one or more targets, at the selected location on the substrate. Using the new model, a high agreement between the simulated and grown films’ thickness and composition across the substrate was obtained. The basis for the high agreement is the use of variable angle spectroscopic ellipsometry to carefully determine [math] by measuring at 794 locations on the 50.8 mm (2 in.) diameter substrates. Factors, such as variation in optical properties and porosity across the plume/calibration films, were considered in the determination of the thicknesses. As test cases, we simulated and deposited (single component) [math] thin films and (CCS) [math] films doped with Cr and N, deposited on 50.8 mm diameter Si wafers. The modeling and simulations are implemented in an opensource Python library, pyPLD.
Journal of Applied Physics, Volume 132, Issue 12, September 2022. <br/>Pulsed laser deposition (PLD) is a powerful technique for prototyping thin film materials, both single component (single composition) films and films with a varying composition (e.g., lateral continuous compositional spread, CCS). In this work, we improve one of the simulation methods used to design the deposition of PLD films: We extend the mathematical model for the material spread on the substrate, [math], for each laser pulse hitting the target, and we use a more accurate method to determine [math] experimentally. The deposition of the material on the substrate is simulated by repetitively adding [math], from one or more targets, at the selected location on the substrate. Using the new model, a high agreement between the simulated and grown films’ thickness and composition across the substrate was obtained. The basis for the high agreement is the use of variable angle spectroscopic ellipsometry to carefully determine [math] by measuring at 794 locations on the 50.8 mm (2 in.) diameter substrates. Factors, such as variation in optical properties and porosity across the plume/calibration films, were considered in the determination of the thicknesses. As test cases, we simulated and deposited (single component) [math] thin films and (CCS) [math] films doped with Cr and N, deposited on 50.8 mm diameter Si wafers. The modeling and simulations are implemented in an opensource Python library, pyPLD.
Improved methods for design of PLD and combinatorial PLD films
10.1063/5.0105298
Journal of Applied Physics
20220922T09:56:32Z
© 2022 Author(s).
Hogne Lysne
Thomas Brakstad
Morten Kildemo
Turid Reenaas

Study on PN heterojunctions associated bending coupling in flexoelectric semiconductor composites considering the effects of sizedependent and symmetrybreaking
https://aip.scitation.org/doi/10.1063/5.0102209?af=R&feed=mostrecent
Journal of Applied Physics, <a href="https://aip.scitation.org/toc/jap/132/12">Volume 132, Issue 12</a>, September 2022. <br/>Under bending deformation, sizedependent and structureassociated strain gradients can occur at the interface of a flexoelectric semiconductor (FS) PN heterojunction. Consequentially, a giant flexoelectric coupling will be induced to significantly enhance the flexoelectric effect of FS structures. To better understand the strain gradient–enhanced modulation performance and also reveal some other new phenomena, in this work, we theoretically and numerically study a beam shaped FS laminated composite subjected to pure bending loads. We first establish a onedimensional theoretical model and then numerically explore the mechanical behaviors of the selected FS beam laminate. During analysis, structural symmetry breaking and size effect are considered by tuning the beam structural size and material parameters. We find that different from piezoelectric semiconductors whose mobile charges are driven by the piezopotential, the mobile charges of FS composites induced by the flexopotential are deterministically associated with strain gradients. Moreover, the strain gradients can exhibit a strong sizedependent effect and are quite sensitive to structural asymmetry and material parameters. We believe that our work can provide a new way to tune the carrier transport and electromechanical characteristics of a PN junction and thus can be useful to guide the nextgeneration flexotronic device designs.
Journal of Applied Physics, Volume 132, Issue 12, September 2022. <br/>Under bending deformation, sizedependent and structureassociated strain gradients can occur at the interface of a flexoelectric semiconductor (FS) PN heterojunction. Consequentially, a giant flexoelectric coupling will be induced to significantly enhance the flexoelectric effect of FS structures. To better understand the strain gradient–enhanced modulation performance and also reveal some other new phenomena, in this work, we theoretically and numerically study a beam shaped FS laminated composite subjected to pure bending loads. We first establish a onedimensional theoretical model and then numerically explore the mechanical behaviors of the selected FS beam laminate. During analysis, structural symmetry breaking and size effect are considered by tuning the beam structural size and material parameters. We find that different from piezoelectric semiconductors whose mobile charges are driven by the piezopotential, the mobile charges of FS composites induced by the flexopotential are deterministically associated with strain gradients. Moreover, the strain gradients can exhibit a strong sizedependent effect and are quite sensitive to structural asymmetry and material parameters. We believe that our work can provide a new way to tune the carrier transport and electromechanical characteristics of a PN junction and thus can be useful to guide the nextgeneration flexotronic device designs.
Study on PN heterojunctions associated bending coupling in flexoelectric semiconductor composites considering the effects of sizedependent and symmetrybreaking
10.1063/5.0102209
Journal of Applied Physics
20220922T09:56:30Z
© 2022 Author(s).
Haoqing Li
Liangliang Chu
Yanbin Li
Guansuo Dui
Qian Deng

Capacitance–voltage characterization of metal–insulator–semiconductor capacitors formed on widebandgap semiconductors with deep dopants such as diamond
https://aip.scitation.org/doi/10.1063/5.0104016?af=R&feed=mostrecent
Journal of Applied Physics, <a href="https://aip.scitation.org/toc/jap/132/12">Volume 132, Issue 12</a>, September 2022. <br/>As diamond possesses only deep dopants, certain conventional physics and characterization methods are not applicable to diamond devices, owing to the explicit or implicit assumption of shallow dopants. To resolve this limitation, the capacitance–voltage (C–V) characteristics of metal–insulator–semiconductor (MIS) capacitors formed on a semiconductor substrate with deep and compensating dopants were successfully formulated. Based on these equations, methods for accurately estimating the MIS capacitor properties were developed and validated through their application in the analysis of an actual MIS capacitor formed on a borondoped hydrogenterminated diamond substrate. The highfrequency C–V characteristic of the capacitor exhibited a prominent dip specific to deep dopants. However, the dip depth was considerably shallower than theoretically expected. This C–V characteristic was accurately reproduced theoretically, assuming the presence of a surficial diamond layer that contains acceptors with an activation energy of 0.23 eV, which is less than the value 0.37 eV for boron, and has a thickness of the extrinsic Debye length (40 nm in this study) or larger. The insulator charge of the MIS capacitor was estimated as −4.6 × 1012 cm−2 in units of electronic charge, which is sufficiently large to induce twodimensional hole gas. The interfacestate density was 1.4 × 1012 cm−2 eV−1 for interfacestate energies of 0.3–0.5 eV above the valence band maximum. Hence, the proposed methodology and the possible presence of the reduced activation energy layer will guide the development of diamondbased devices.
Journal of Applied Physics, Volume 132, Issue 12, September 2022. <br/>As diamond possesses only deep dopants, certain conventional physics and characterization methods are not applicable to diamond devices, owing to the explicit or implicit assumption of shallow dopants. To resolve this limitation, the capacitance–voltage (C–V) characteristics of metal–insulator–semiconductor (MIS) capacitors formed on a semiconductor substrate with deep and compensating dopants were successfully formulated. Based on these equations, methods for accurately estimating the MIS capacitor properties were developed and validated through their application in the analysis of an actual MIS capacitor formed on a borondoped hydrogenterminated diamond substrate. The highfrequency C–V characteristic of the capacitor exhibited a prominent dip specific to deep dopants. However, the dip depth was considerably shallower than theoretically expected. This C–V characteristic was accurately reproduced theoretically, assuming the presence of a surficial diamond layer that contains acceptors with an activation energy of 0.23 eV, which is less than the value 0.37 eV for boron, and has a thickness of the extrinsic Debye length (40 nm in this study) or larger. The insulator charge of the MIS capacitor was estimated as −4.6 × 1012 cm−2 in units of electronic charge, which is sufficiently large to induce twodimensional hole gas. The interfacestate density was 1.4 × 1012 cm−2 eV−1 for interfacestate energies of 0.3–0.5 eV above the valence band maximum. Hence, the proposed methodology and the possible presence of the reduced activation energy layer will guide the development of diamondbased devices.
Capacitance–voltage characterization of metal–insulator–semiconductor capacitors formed on widebandgap semiconductors with deep dopants such as diamond
10.1063/5.0104016
Journal of Applied Physics
20220926T09:33:12Z
© 2022 Author(s).
Atsushi Hiraiwa
Satoshi Okubo
Masahiko Ogura
Yu Fu
Hiroshi Kawarada

Tailoring of defects dependent magnetic properties of swift heavy ion irradiated CeO2 for spintronics application
https://aip.scitation.org/doi/10.1063/5.0088882?af=R&feed=mostrecent
Journal of Applied Physics, <a href="https://aip.scitation.org/toc/jap/132/12">Volume 132, Issue 12</a>, September 2022. <br/>The present investigation reports the swift heavy ion induced effects on cerium oxide (CeO2) thin films. These thin films were deposited on Si (111) substrates by the electronbeam evaporation method and irradiated by a 100 MeV O7+ ion beam with different ion fluences. Xray diffraction analysis of these films confirms the stable fluorite phase of CeO2 even after the higher fluence of irradiations. Raman measurement also supports the presence of the F2g phase of CeO2 and the presence of defect states. The Gaussian deconvolution of photoluminescence (PL) spectra reveals various defectassociated peaks. The broad peaks in the PL spectra are associated with oxygen vacancies and are redshifted (494–520 nm) with ion fluences. The surface morphological images show the modification in the surface roughness with ion irradiation and the regrowth of smaller circularformed nanoparticles on the surface is observed at the fluence of 5 × 1011 ions/cm2. Magnetic measurements show an enhancement in magnetic ordering with ion irradiation. All the samples demonstrate room temperature ferromagnetism with magnetic saturation (Ms) up to 14.57 emu/cm3. The saturation magnetization in irradiated thin films is directly correlated to the area under the peak of defectassociated PL emission. The mechanism such as the oxygen vacancybased Fcenter exchange model is considered to understand the enhancement of ferromagnetism in ion irradiated CeO2 thin films. Some popular theoretical models are also employed to determine various magnetic parameters.
Journal of Applied Physics, Volume 132, Issue 12, September 2022. <br/>The present investigation reports the swift heavy ion induced effects on cerium oxide (CeO2) thin films. These thin films were deposited on Si (111) substrates by the electronbeam evaporation method and irradiated by a 100 MeV O7+ ion beam with different ion fluences. Xray diffraction analysis of these films confirms the stable fluorite phase of CeO2 even after the higher fluence of irradiations. Raman measurement also supports the presence of the F2g phase of CeO2 and the presence of defect states. The Gaussian deconvolution of photoluminescence (PL) spectra reveals various defectassociated peaks. The broad peaks in the PL spectra are associated with oxygen vacancies and are redshifted (494–520 nm) with ion fluences. The surface morphological images show the modification in the surface roughness with ion irradiation and the regrowth of smaller circularformed nanoparticles on the surface is observed at the fluence of 5 × 1011 ions/cm2. Magnetic measurements show an enhancement in magnetic ordering with ion irradiation. All the samples demonstrate room temperature ferromagnetism with magnetic saturation (Ms) up to 14.57 emu/cm3. The saturation magnetization in irradiated thin films is directly correlated to the area under the peak of defectassociated PL emission. The mechanism such as the oxygen vacancybased Fcenter exchange model is considered to understand the enhancement of ferromagnetism in ion irradiated CeO2 thin films. Some popular theoretical models are also employed to determine various magnetic parameters.
Tailoring of defects dependent magnetic properties of swift heavy ion irradiated CeO2 for spintronics application
10.1063/5.0088882
Journal of Applied Physics
20220927T11:34:54Z
© 2022 Author(s).
Anshu Singh
Richa Saini
Pawan Kumar
Asokan Kandasami

Effects of selfirradiation on deuterium retention and reflectivity of molybdenum, fusion plasmafacing material: Combined experimental and modeling study
https://aip.scitation.org/doi/10.1063/5.0099051?af=R&feed=mostrecent
Journal of Applied Physics, <a href="https://aip.scitation.org/toc/jap/132/12">Volume 132, Issue 12</a>, September 2022. <br/>Molybdenum is used as plasmafacing material in tokamaks and as material for plasma optical diagnostics mirrors. Harsh conditions of neutron irradiation, exposure to hydrogen isotopes and helium ions, and high operating temperatures result in degradation of the molybdenum surface and ultimately limit their lifetime in a fusion power plant. In the current paper, intake and subsequent thermal release of deuterium from selfirradiated by high energy (1 MeV) ions molybdenum as a function of irradiation dose are investigated. Several characteristic temperature regions where deuterium release takes place are identified and attributed to trapping of deuterium in intrinsic and radiationinduced microstructure defects. This attribution is further validated by molecular dynamics modeling, which confirms that increase and saturation of vacancy concentration found in simulations follows increase and saturation of experimentally determined deuterium content. Deuterium inventory and vacancy content saturate at a damage level of around 0.2 dpa (displacement per atom), similar to recent modeling and experimental studies of iron and tungsten. Reflectivity measurements of irradiated molybdenum show that it is only slightly affected by damage up to 1 dpa.
Journal of Applied Physics, Volume 132, Issue 12, September 2022. <br/>Molybdenum is used as plasmafacing material in tokamaks and as material for plasma optical diagnostics mirrors. Harsh conditions of neutron irradiation, exposure to hydrogen isotopes and helium ions, and high operating temperatures result in degradation of the molybdenum surface and ultimately limit their lifetime in a fusion power plant. In the current paper, intake and subsequent thermal release of deuterium from selfirradiated by high energy (1 MeV) ions molybdenum as a function of irradiation dose are investigated. Several characteristic temperature regions where deuterium release takes place are identified and attributed to trapping of deuterium in intrinsic and radiationinduced microstructure defects. This attribution is further validated by molecular dynamics modeling, which confirms that increase and saturation of vacancy concentration found in simulations follows increase and saturation of experimentally determined deuterium content. Deuterium inventory and vacancy content saturate at a damage level of around 0.2 dpa (displacement per atom), similar to recent modeling and experimental studies of iron and tungsten. Reflectivity measurements of irradiated molybdenum show that it is only slightly affected by damage up to 1 dpa.
Effects of selfirradiation on deuterium retention and reflectivity of molybdenum, fusion plasmafacing material: Combined experimental and modeling study
10.1063/5.0099051
Journal of Applied Physics
20220928T11:39:17Z
© 2022 Author(s).
M. Yu. Lavrentiev
A. Hollingsworth
J. Hess
S. Davies
A. Wohlers
B. Thomas
H. Salter
A. BaronWiechec
I. Jepu
Y. Zayachuk
N. Peng

Highpressure evolution of the refractive index of MgO up to 140 GPa
https://aip.scitation.org/doi/10.1063/5.0106626?af=R&feed=mostrecent
Journal of Applied Physics, <a href="https://aip.scitation.org/toc/jap/132/12">Volume 132, Issue 12</a>, September 2022. <br/>Refractive index provides fundamental insights into the electronic structure of materials. At high pressure, however, the determination of refractive index and its wavelength dispersion is challenging, which limits our understanding of how physical properties of even simple materials, such as MgO, evolve with pressure. Here, we report on the measurement of roomtemperature refractive index of MgO up to ∼140 GPa. The refractive index of MgO at 600 nm decreases by ∼2.4% from ∼1.737 at 1 atm to ∼1.696 (±0.017) at ∼140 GPa. Despite the index at 600 nm is essentially pressure independent, the absolute wavelength dispersion of the refractive index at 550–870 nm decreases by ∼28% from ∼0.015 at 1 atm to ∼0.011 (±8.04 × 10−4) at ∼103 GPa. Singleeffectiveoscillator analysis of our refractive index data suggests that the bandgap of MgO increases by ∼1.1 eV from 7.4 eV at 1 atm to ∼8.5 (±0.6) eV at ∼103 GPa.
Journal of Applied Physics, Volume 132, Issue 12, September 2022. <br/>Refractive index provides fundamental insights into the electronic structure of materials. At high pressure, however, the determination of refractive index and its wavelength dispersion is challenging, which limits our understanding of how physical properties of even simple materials, such as MgO, evolve with pressure. Here, we report on the measurement of roomtemperature refractive index of MgO up to ∼140 GPa. The refractive index of MgO at 600 nm decreases by ∼2.4% from ∼1.737 at 1 atm to ∼1.696 (±0.017) at ∼140 GPa. Despite the index at 600 nm is essentially pressure independent, the absolute wavelength dispersion of the refractive index at 550–870 nm decreases by ∼28% from ∼0.015 at 1 atm to ∼0.011 (±8.04 × 10−4) at ∼103 GPa. Singleeffectiveoscillator analysis of our refractive index data suggests that the bandgap of MgO increases by ∼1.1 eV from 7.4 eV at 1 atm to ∼8.5 (±0.6) eV at ∼103 GPa.
Highpressure evolution of the refractive index of MgO up to 140 GPa
10.1063/5.0106626
Journal of Applied Physics
20220928T11:39:17Z
© 2022 Author(s).
Lukas Schifferle
Sergio Speziale
Sergey S. Lobanov

Thorium dicarbide under high pressure and high temperature: Ab initio investigation
https://aip.scitation.org/doi/10.1063/5.0102537?af=R&feed=mostrecent
Journal of Applied Physics, <a href="https://aip.scitation.org/toc/jap/132/12">Volume 132, Issue 12</a>, September 2022. <br/>A systematic study on the structural stability of thorium dicarbide (ThC2) under hydrostatic compression has been carried out by exploiting the evolutionary structure search algorithm as implemented in the universal structure predictor: evolutionary Xtallography (USPEX) code in conjunction with the ab initio electronic band structure calculation method. At ambient conditions, ThC2 exists in a monoclinic crystallographic phase with space group (SG) C2/c. Our calculations under generalized gradient approximation (GGA) predict the highpressure structural sequence of monoclinicI (SG C2/c) → monoclinicII (SG C2/m) → orthorhombicI (SG Pmma) → orthorhombicII (SG Immm) → hexagonal (SG P6/mmm) for this material with transition pressures of ∼3.3, 58.3, 191.6, and 255 GPa, respectively. Out of this theoretically predicted highpressure structural phase transition sequence, only the first transition, i.e., monoclinicI → monoclinicII, could be compared with the available highpressure experimental study by Guo et al. [Sci. Rep. 7, 45872 (2017)]. The theoretically determined phase transition qualitatively agrees with the experimental results [Y. Guo et al. Sci. Rep. 7, 45872 (2017)]. Interestingly, our predicted intermediate orthorhombicI (SG Pmma) phase has an enthalpy lower than that of the previously predicted orthorhombic Cmmm phase by Guo et al. [Sci. Rep. 7, 45872 (2017)]. The highpressure structural sequence so predicted through static lattice calculations has been further substantiated by confirming the elastic and lattice dynamic stability of each structure in the pressure regime of its structural stability. Additionally, the superconducting transition temperature for all these structures has been determined and it is found that the monoclinicII (C2/m) phase has the highest transition temperature of 17 K at 5 GPa. Furthermore, the thermophysical properties along with the temperatureinduced phase transitions in ThC2 have also been investigated through both the lattice dynamic simulations (within quasiharmonic approximation) and ab initio molecular dynamics simulations.
Journal of Applied Physics, Volume 132, Issue 12, September 2022. <br/>A systematic study on the structural stability of thorium dicarbide (ThC2) under hydrostatic compression has been carried out by exploiting the evolutionary structure search algorithm as implemented in the universal structure predictor: evolutionary Xtallography (USPEX) code in conjunction with the ab initio electronic band structure calculation method. At ambient conditions, ThC2 exists in a monoclinic crystallographic phase with space group (SG) C2/c. Our calculations under generalized gradient approximation (GGA) predict the highpressure structural sequence of monoclinicI (SG C2/c) → monoclinicII (SG C2/m) → orthorhombicI (SG Pmma) → orthorhombicII (SG Immm) → hexagonal (SG P6/mmm) for this material with transition pressures of ∼3.3, 58.3, 191.6, and 255 GPa, respectively. Out of this theoretically predicted highpressure structural phase transition sequence, only the first transition, i.e., monoclinicI → monoclinicII, could be compared with the available highpressure experimental study by Guo et al. [Sci. Rep. 7, 45872 (2017)]. The theoretically determined phase transition qualitatively agrees with the experimental results [Y. Guo et al. Sci. Rep. 7, 45872 (2017)]. Interestingly, our predicted intermediate orthorhombicI (SG Pmma) phase has an enthalpy lower than that of the previously predicted orthorhombic Cmmm phase by Guo et al. [Sci. Rep. 7, 45872 (2017)]. The highpressure structural sequence so predicted through static lattice calculations has been further substantiated by confirming the elastic and lattice dynamic stability of each structure in the pressure regime of its structural stability. Additionally, the superconducting transition temperature for all these structures has been determined and it is found that the monoclinicII (C2/m) phase has the highest transition temperature of 17 K at 5 GPa. Furthermore, the thermophysical properties along with the temperatureinduced phase transitions in ThC2 have also been investigated through both the lattice dynamic simulations (within quasiharmonic approximation) and ab initio molecular dynamics simulations.
Thorium dicarbide under high pressure and high temperature: Ab initio investigation
10.1063/5.0102537
Journal of Applied Physics
20220928T11:40:17Z
© 2022 Author(s).
B. D. Sahoo
K. D. Joshi

Publisher's Note: “A stepbystep guide to perform xray photoelectron spectroscopy” [J. Appl. Phys. 132, 011101 (2022)]
https://aip.scitation.org/doi/10.1063/5.0123879?af=R&feed=mostrecent
Journal of Applied Physics, <a href="https://aip.scitation.org/toc/jap/132/12">Volume 132, Issue 12</a>, September 2022. <br/>
Journal of Applied Physics, Volume 132, Issue 12, September 2022. <br/>
Publisher's Note: “A stepbystep guide to perform xray photoelectron spectroscopy” [J. Appl. Phys. 132, 011101 (2022)]
10.1063/5.0123879
Journal of Applied Physics
20220920T09:38:48Z
© 2022 Author(s).
Grzegorz Greczynski
Lars Hultman

Erratum: “Hightemperature effect on the sound absorption of cylindrically perforated porous materials” [J. Appl. Phys. 130, 105101 (2021)]
https://aip.scitation.org/doi/10.1063/5.0123986?af=R&feed=mostrecent
Journal of Applied Physics, <a href="https://aip.scitation.org/toc/jap/132/12">Volume 132, Issue 12</a>, September 2022. <br/>
Journal of Applied Physics, Volume 132, Issue 12, September 2022. <br/>
Erratum: “Hightemperature effect on the sound absorption of cylindrically perforated porous materials” [J. Appl. Phys. 130, 105101 (2021)]
10.1063/5.0123986
Journal of Applied Physics
20220928T11:54:17Z
© 2022 Author(s).
Xuewei Liu
Fengxian Xin
Chuanzeng Zhang

Erratum: “Thermal transport in silvercoated polymer sphere composites by the bidirectional 3ω method” [J. Appl. Phys. 131, 125107 (2022)]
https://aip.scitation.org/doi/10.1063/5.0123921?af=R&feed=mostrecent
Journal of Applied Physics, <a href="https://aip.scitation.org/toc/jap/132/12">Volume 132, Issue 12</a>, September 2022. <br/>
Journal of Applied Physics, Volume 132, Issue 12, September 2022. <br/>
Erratum: “Thermal transport in silvercoated polymer sphere composites by the bidirectional 3ω method” [J. Appl. Phys. 131, 125107 (2022)]
10.1063/5.0123921
Journal of Applied Physics
20220928T11:40:17Z
© 2022 Author(s).
Susanne Sandell
Thorstein Wang
Emigdio ChávezÁngel
Helge Kristiansen
Zhiliang Zhang
Jianying He