In-situ field induced enhancement of damping-like field and field-free switching in perpendicularly coupled Pt/Co and CoFeB bilayers sandwiched by an ultrathin PtMn/Ta layer

Abstract

Field-free switching of perpendicular magnetization and improvement of spin-orbit torque (SOT) efficiency are the keys for SOT-based devices towards ultrafast and low-power memory and computing applications. In this letter, we investigated pulse current induced magnetization switching and its efficiency in perpendicularly coupled Pt/Co and CoFeB bilayers sandwiched by an ultrathin PtMn/Ta layer, prepared in the presence/absence of an in-plane in-situ field. It is found that both the SOT efficiency and field-free switching are enhanced by the presence of the in-situ field. Quantitative characterization indicates that the damping-like field, HDL, is boosted by an amount of up to 45%. The tilted spin texture at the Co/PtMn interface caused by the presence of the in-situ field may play a role on the enhancement of SOT efficiency and field-free switching. Our findings not only provide a promising approach for SOT efficiency enhancement but also offer a possible layer stack for the integration of a full magnetic tunnel junction (MTJ) for low power memory and computing.