Spin-orbit torques induced by interface-generated spin currents

TL;DR

This paper demonstrates field-free switching in magnetic trilayers by leveraging a novel interface-generated spin current, advancing energy-efficient control in spintronic devices.

Contribution

It reveals a new interface-generated spin-orbit torque mechanism that enables magnetic switching without external magnetic fields.

Findings

Field-free switching achieved in magnetic trilayers.

Torque depends on bottom layer magnetization, indicating interface origin.

Interface-generated spin current differs from bulk effects.

Abstract

Magnetic torques generated through spin-orbit coupling promise energy-efficient spintronic devices. It is important for applications to control these torques so that they switch films with perpendicular magnetizations without an external magnetic field. One suggested approach uses magnetic trilayers in which the torque on the top magnetic layer can be manipulated by changing the magnetization of the bottom layer. Spin currents generated in the bottom magnetic layer or its interfaces transit the spacer layer and exert a torque on the top magnetization. Here we demonstrate field-free switching in such structures and attribute it to a novel spin current generated at the interface between the bottom layer and the spacer layer. The measured torque has a distinct dependence on the bottom layer magnetization which is consistent with this interface-generated spin current but not the anticipated bulk effects. This other interface-generated spin-orbit torque will enable energy-efficient control of spintronic devices.