Spin torque-driven switching of exchange bias in a spin valve

We show that the strength and direction of the exchange bias in a spin valve can be changed and recovered by applying a spin-polarized current pulse. In other words, once the exchange bias has been changed by a spin-polarized current pulse with the external magnetic field antiparallel to the exchange bias direction, it can be returned to the initial state by a current pulse of the same magnitude with reversal of the external field. Furthermore, the exchange bias field reverts to the same magnitude, irrespective of whether one or multiple current pulses are applied. Based on a model for spin-momentum transfer, the experimental observations can be rationalized in terms of changing micromagnetic distributions at the ferromagnet/antiferromagnet interface. (c) 2009 American Institute of Physics. [doi:10.1063/1.3236572]