Current-Driven Magnetoresistance Oscillations in Asymmetric Spin Valves

Abstract

Within the macroscopic model we have calculated spin-transfer torque in asymmetric spin valves in the diffusive transport limit.Such systems exhibit a non-standard angular dependence of the torque, which leads to currentinduced precessional modes at zero external magnetic field. We have found that the frequency of magnetoresistance oscillations exhibits hysteretic behavior when the system is driven between two steady precessional regimes. A finite temperature can suppress the irreversibility and give rise to bistable regime where, both the precessional regimes coexist.