Low switching current in a modified exchange-biased spin valve via antiferromagnetic spin transfer torque

Abstract

We analyze the current-induced spin transfer torque and magnetization reversal properties in an exchanged-biased spin valve (EBSV) structure FM2/NM/FM1/AFM, taking into consideration the exchange interaction between the ferromagnetic (FM) and the antiferromagnetic (AFM) layers. The passage of the spin current above a certain threshold value causes the magnetization to switch in some parts of the AFM layer. This in turn leads to a change in the magnitude and direction of the exchange-bias field, which can subsequently assist or hinder the magnetization switching of the adjacent FM layer and results in so-called inverse current-induced magnetization switching for a weakly-biased EBSV structure. The requisite critical current density to switch the AFM layer is theoretically found to be lower than that for the FM layer, which provides us a potential method to substantially reduce the critical current density for the spin transfer switching in EBSV-based devices.