Thermal effect and current pulse durations on spin-transfer magnetization switching in MgO-based tunnel junctions

摘要

We have measured current-induced magnetization switching for MgO-based tunnel junctions with different current amplitudes and pulse durations at room temperature. The pulse widths ranged from 50 μs to 1 ms and the current ratios J/J_(C0) ranged from 0.4 to 0.97 (J_(C0) is the intrinsic critical current density). The results showed that the model of thermal assisted spin-transfer switching works well for the range of low to medium current ratio. However, for high current ratio, the switching probability did not fit the simple exponential function but grew with the current ratio linearly. The corresponding values of energy barrier as the current ratio approaches to unity indicated that thermal activation may still play an important role in magnetization switching.