MgO-based magnetic tunnel junction sensors array for non-destructive testing applications

D. W.  Guo; F. A.  Cardoso; R.  Ferreira; E.  Paz; S.  Cardoso; P. P.  Freitas

doi:10.1063/1.4863933

Abstract

A MgO-based magnetic tunnel junction

(MTJ)

sensor including 72 MTJs in series with 50 × 50 μm² was successfully microfabricated. Due to a two-step annealing strategy, a linear transfer curve was obtained. The tunneling magnetoresistance (TMR) value is as high as 159% and the sensitivity reaches 2.9%/Oe. The field detectivity exhibits the lowest value at 1 V bias current, attaining 1.76 nT/Hz^0.5 and 170 pT/Hz^0.5 for 10 Hz and 1 kHz, respectively. The results show that the sensor could be applied in non-destructive testing systems which are used for detecting small defects inside conductive materials.

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