The straining effect on tunneling resistance of Co/AlO_x/Co/lrMn junctions

摘要

The authors have fabricated a series of Co/AlO_x(d_0)/Co/IrMn magnetic tunnel junctions (MTJs), with d_0 = 12-30 A. They can be used as ultrasensitive strain gauges. From the resistance (R) versus strain (Δε) curve, the authors find that the maximum value of the gauge factor (γ_(max)) is as large as 5000-20000 in the low-strain (|Δε| ≤ 25 x 10~(-6)) range. Furthermore, the response is linear. Two mechanisms are proposed to explain the piezoresistance behavior of these MTJs: one is due to the tunneling magnetoresistance effect (the magnetic origin) and the other due to the ordinary tunneling effect (the nonmagnetic origin).