Designing Magnetic Topological Insulator Trilayers for Highly-Efficient Spin-Orbit Torque Switching

TL;DR

This paper demonstrates how magnetic topological insulator trilayers can be engineered to achieve highly efficient spin-orbit torque switching, enabling electrical control of edge current chirality for low-power spintronic devices.

Contribution

It introduces a method to control SOT switching in magnetic TIs via substrate-induced chemical potential asymmetry and heterostructure design, advancing spintronic device development.

Findings

SOT-driven magnetization reversal is governed by substrate-induced charging effects.

Switching polarity and efficiency can be tuned by heterostructure design, gate voltage, and magnetic field.

Chemical potential asymmetry is identified as the key to large SOT switching ratios.

Abstract

Spin-orbit torque (SOT) enables efficient electrical control of magnetization, offering a pathway towards low-power spintronic devices. Magnetic topological insulators (TIs), with spin-momentum-locked surface states and intrinsic ferromagnetism, provide a unique platform for realizing SOT switching of edge current chirality in quantum anomalous Hall (QAH) insulators. In this work, we employ molecular beam epitaxy to synthesize a series of magnetic TI trilayers with controlled layer thicknesses on heat-treated SrTiO3(111) substrates. Electrical transport measurements reveal that SOT-driven magnetization reversal and the associated switching of edge current chirality are governed by the SrTiO3(111) substrate-induced charging effect, which generates an asymmetric chemical-potential alignment between the top and bottom magnetic TI layers. Furthermore, we demonstrate that the switching polarity and efficiency can be tuned through heterostructure design, gate voltage, and in-plane magnetic field, consistent with SOT symmetry. These findings identify chemical potential asymmetry as the origin of the large SOT switching ratio in magnetic TI trilayers and establish a route for electrical control of edge current chirality in QAH insulators. This work advances the understanding of SOT switching mechanism in magnetic topological materials and paves the way for next-generation, energy-efficient QAH-based logic and memory devices.