Enhanced spin-orbit torque via interface engineering in Pt/CoFeB/MgO heterostructures

TL;DR

This paper demonstrates that inserting a Ti layer at the interface of Pt/CoFeB heterostructures significantly enhances spin-orbit torque and switching efficiency through interface-generated spin currents and improved spin transparency.

Contribution

The study introduces a novel interface engineering method using Ti insertion to boost spin-orbit torque in Pt/CoFeB heterostructures, revealing new mechanisms for efficiency enhancement.

Findings

Enhanced spin-orbit torque with Ti insertion.

Increased switching efficiency in heterostructures.

Interface-generated spin current contributes to enhancement.

Abstract

Spin-orbit torque facilitates efficient magnetization switching via an in-plane current in perpendicularly magnetized heavy metal/ferromagnet heterostructures. The efficiency of spin-orbit-torque-induced switching is determined by the charge-to-spin conversion arising from either bulk or interfacial spin-orbit interactions, or both. Here, we demonstrate that the spin-orbit torque and the resultant switching efficiency in Pt/CoFeB systems are significantly enhanced by an interfacial modification involving Ti insertion between the Pt and CoFeB layers. Spin pumping and X-ray magnetic circular dichroism experiments reveal that this enhancement is due to an additional interface-generated spin current of the nonmagnetic interface and/or improved spin transparency achieved by suppressing the proximity-induced moment in the Pt layer. Our results demonstrate that interface engineering affords an effective approach to improve spin-orbit torque and thereby magnetization switching efficiency.