Large unidirectional spin Hall and Rashba-Edelstein magnetoresistance in topological insulator/magnetic insulator heterostructures

TL;DR

This paper reports a significant enhancement of unidirectional spin Hall and Rashba-Edelstein magnetoresistance in magnetic insulator/topological insulator heterostructures, enabling efficient current-induced magnetization switching for memory applications.

Contribution

It introduces a new heterostructure configuration that achieves much larger USRMR than previous metal-based devices, advancing spintronic memory technology.

Findings

USRMR in heterostructures is an order of magnitude larger than in all-metal bilayers.

Demonstrated current-induced magnetization switching using USRMR.

Proposed a prototype memory device utilizing these effects.

Abstract

Thanks to its unique symmetry, the unidirectional spin Hall and Rashba-Edelstein magnetoresistance (USRMR) is of great fundamental and practical interest, particularly in the context of reading magnetization states in two-terminal spin-orbit torque switching memory and logic devices. Recent studies show that topological insulators could improve USRMR amplitude. However, the topological insulator device configurations studied so far in this context, namely ferromagnetic metal/topological insulator bilayers and magnetically doped topological insulators, suffer from current shunting by the metallic layer and low Curie temperature, respectively. Here, we report large USRMR in a new material category - magnetic insulator/topological insulator bi-layered heterostructures. Such structures exhibit USRMR that is about an order of magnitude larger than the highest values reported so far in all-metal Ta/Co bilayers. We also demonstrate current-induced magnetization switching aided by an Oersted field, and electrical read out by the USRMR, as a prototype memory device.