Giant spin-orbit torque in a single ferrimagnetic metal layer

TL;DR

This paper demonstrates highly efficient spin-orbit torque in a single ferrimagnetic layer, enabling potential ultra-high-speed, energy-efficient spintronic devices by overcoming previous excitation and detection challenges.

Contribution

It reveals that a single layer of Mn2RuxGa exhibits remarkably strong spin-orbit fields, surpassing those in bilayer structures, and shows the antidamping torque can sustain self-oscillation.

Findings

Spin-orbit fields approach 0.1x10^-10 T m^2/A at low current density.

The antidamping torque can sustain self-oscillation in the material.

Spin electronics can enable ultra high-speed, energy-efficient information transfer.

Abstract

Antiferromagnets and compensated ferrimagnets offer opportunities to investigate spin dynamics in the 'terahertz gap' because their resonance modes lie in the 0.3 THz to 3 THz range. Despite some inherent advantages when compared to ferromagnets, these materials have not been extensively studied due to difficulties in exciting and detecting the high-frequency spin dynamics, especially in thin films. Here we show that spin-obit torque in a single layer of the highly spin-polarized compensated ferrimagnet Mn2RuxGa is remarkably efficient at generating spin-orbit fields \mu_0H_eff, which approach 0.1x10-10 T m2/A in the low-current density limit -- almost a thousand times the Oersted field, and one to two orders of magnitude greater than the effective fields in heavy metal/ferromagnet bilayers. From an analysis of the harmonic Hall effect which takes account of the thermal contributions from the anomalous Nernst effect, we show that the antidamping component of the spin-orbit torque is sufficient to sustain self-oscillation. Our study demonstrates that spin electronics has the potential to underpin energy-frugal, chip-based solutions to the problem of ultra high-speed information transfer.