No Access Submitted: 08 May 2020 Accepted: 25 June 2020 Published Online: 14 July 2020
Appl. Phys. Lett. 117, 022406 (2020);
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  • Shuichi Iwakiri
  • Satoshi Sugimoto
  • Yasuhiro Niimi
  • Kensuke Kobayashi
  • Yusuke Kozuka
  • Yukiko K. Takahashi
  • Shinya Kasai
We investigate the spectral characteristics of a spin torque oscillator (STO) excited by the spin Hall-induced spin current. We observe that the modest spin current injection triggers the conventional single peak oscillating behavior of the STO. As the spin current is further increased to enter the non-linear regime, we find the transition of the spectrum from a single peak to a multipeak structure whose frequency spacing is constant. This behavior can be primarily explained by the extremely broadened peak of the STO, which is accompanied by the frequency-dependent filtering by the transmission line. To explain the observation more quantitatively, we also discuss that the multipeak may reflect the characteristics of the intrinsic dynamics of the STO in the non-linear regime.
This work was partially supported by JSPS KAKENHI Grant Nos. JP17K18892, JP18J20527, JP19H00656, JP19H05826, JP16H05964, and JP26103002, RIEC, Tohoku University. The authors acknowledge Y. Suzuki and T. Taniguchi for fruitful discussions. The authors also acknowledge M. Takahagi for technical support.