Room temperature magnetization switching in topological insulator-ferromagnet heterostructures by spin-orbit torques

TL;DR

This paper demonstrates room temperature magnetization switching in a Bi2Se3/NiFe heterostructure driven by spin-orbit torques, with high efficiency and low current density, advancing topological insulator spintronics.

Contribution

It provides the first direct evidence of room temperature SOT-driven magnetization switching in a TI/ferromagnet heterostructure using Bi2Se3, with high charge-to-spin conversion efficiency.

Findings

Giant SOT-driven switching observed at room temperature

Charge to spin conversion efficiency of ~1-1.75

Low switching current density of ~6x10^5 A/cm^2

Abstract

Topological insulators (TIs) with spin momentum locked topological surface states (TSS) are expected to exhibit a giant spin-orbit torque (SOT) in the TI/ferromagnet systems. To date, the TI SOT driven magnetization switching is solely reported in a Cr doped TI at 1.9 K. Here, we directly show giant SOT driven magnetization switching in a Bi2Se3/NiFe heterostructure at room temperature captured using a magneto-optic Kerr effect microscope. We identify a large charge to spin conversion efficiency of ~1-1.75 in the thin TI films, where the TSS is dominant. In addition, we find the current density required for the magnetization switching is extremely low, ~6x10^5 A cm-2, which is one to two orders of magnitude smaller than that with heavy metals. Our demonstration of room temperature magnetization switching of a conventional 3d ferromagnet using Bi2Se3 may lead to potential innovations in TI based spintronic applications.