Thermally activated switching rate of a nanomagnet in the presence of spin torque

Abstract

The current dependence of the spin torque switching rate in a thermally activated region of an in-plane magnetized system was studied. The logarithm of the switching rate depended nonlinearly on current in the high-current region, I_{c} < I < I_{c}^{*}, where I_{c} and I_{c}^{*} are critical currents distinguishing the stability of the magnetization. We also found that the attempt frequency had a minimum around I_{c}, and that the attempt frequency at I_{c} was three orders of magnitude smaller than that at zero current, contrary to the assumption in previous analyses of experiments that it remains constant.