Efficient Spin-Orbit Torque Switching with Non-Epitaxial Chalcogenide Heterostructures

TL;DR

This paper demonstrates that non-epitaxial Bi$_{x}$Te$_{1-x}$/ferromagnet heterostructures, prepared via conventional sputtering, exhibit giant spin-orbit torque efficiencies without the need for topologically-protected surface states, enabling potential spintronic applications.

Contribution

It introduces a method to achieve high SOT efficiencies using non-epitaxial chalcogenide heterostructures, bypassing the need for epitaxial growth and topological surface states.

Findings

Achieved SOT efficiencies >100% at room temperature.

Demonstrated current-induced SOT switching in non-epitaxial heterostructures.

Showed potential for use in future spin-orbit torque magnetic memory devices.

Abstract

The spin-orbit torques (SOTs) generated from topological insulators (TIs) have gained increasing attention in recent years. These TIs, which are typically formed by epitaxially grown chalcogenides, possess extremely high SOT efficiencies and have great potential to be employed in the next-generation spintronics devices. However, epitaxy of these chalcogenides is required to ensure the existence of topologically-protected surface state (TSS), which limits the feasibility of using these materials in industry. In this work, we show that non-epitaxial Bi$_{x}$Te$_{1-x}$/ferromagnet heterostructures prepared by conventional magnetron sputtering possess giant SOT efficiencies even without TSS. Through harmonic voltage measurement and hysteresis loop shift measurement, we find that the damping-like SOT efficiencies originated from the bulk spin-orbit interactions of such non-epitaxial heterostructures can reach values greater than 100% at room temperature. We further demonstrate current-induced SOT switching in these Bi$_{x}$Te$_{1-x}$-based heterostructures with thermally stable ferromagnetic layers, which indicates that such non-epitaxial chalcogenide materials can be potential efficient SOT sources in future SOT magnetic memory devices.