Asymmetric spin torque transfer in nano GMR device with perpendicular anisotropy

Spin torque transfer behaviors in giant magnetoresistive (GMR) devices with perpendicular anisotropy were investigated. The critical switching current density could be effectively reduced by an inserted nano-current-channel layer through the current confined effect and the magnetic exchange coupling composite effect. Depending on the location of the nano-current-channel layer inside the device, the reduction of the critical switching current density could be symmetric (or asymmetric) for the switching processes between parallel and anti parallel configurations. With strong current confined and exchange coupling composite effects, the reduction is up to 52% for parallel → anti-parallel switching while it is only 31% for anti-parallel → parallel switching.