Current-pulse-induced magnetic switching in standard and nonstandard spin-valves: Theory and numerical analysis

Magnetization switching due to a current pulse in symmetric and asymmetric spin-valves is studied theoretically within the macrospin model. The switching process and the corresponding switching parameters are shown to depend significantly on the pulse duration and also on the interplay between the torques due to spin transfer and external magnetic field. This interplay leads to peculiar features in the corresponding phase diagram. These features in standard spin-valves, where the spin-transfer torque stabilizes one of the magnetic configurations (either parallel or antiparallel) and destabilizes the opposite one, are different from those in nonstandard (asymmetric) spin-valves, where both collinear configurations are stable for one current orientation and unstable for the opposite one. Following this we propose a scheme of ultrafast current-induced switching in nonstandard spin-valves, based on a sequence of two current pulses.