Maximizing Spin-Orbit Torque Generated by the Spin Hall Effect of Pt

TL;DR

This paper reviews recent advances in enhancing spin-orbit torque efficiency in platinum-based heterostructures, focusing on increasing spin Hall ratio and interface transmissivity to enable practical spin-orbitronic devices.

Contribution

It summarizes recent progress in understanding spin current physics, interfacial transport, and measurement techniques for improving Pt-based spin-orbit torque applications.

Findings

Enhanced spin Hall ratio improves torque efficiency.

Interfacial engineering increases spin transmissivity.

Progress towards practical spin-orbit torque memory devices.

Abstract

Efficient generation of spin-orbit torques (SOTs) is central for the exciting field of spin-orbitronics. Platinum, the archetypal spin Hall material, has the potential to be an outstanding provider for spin-orbit torques due to its giant spin Hall conductivity, low resistivity, high stabilities, and the ability to be compatible with CMOS circuits. However, pure clean-limit Pt with low resistivity still provides a low damping-like spin-orbit torque efficiency, which limits its practical applications. The efficiency of spin-orbit torque in Pt-based magnetic heterostructures can be improved considerably by increasing the spin Hall ratio of Pt and spin transmissivity of the interfaces. Here we reviews recent advances in understanding the physics of spin current generation, interfacial spin transport, and the metrology of spin-orbit torques, and summarize progress towards the goal of Pt-based spin-orbit torque memories and logic that are fast, efficient, reliable, scalable, and non-volatile.