Electronic control of the spin-wave damping in a magnetic insulator

TL;DR

This paper demonstrates that spin-wave damping in a magnetic insulator can be controlled by injecting a dc current in an adjacent metal, enabling damping reduction or enhancement, with potential for auto-oscillation applications.

Contribution

It shows experimental control of spin-wave damping via in-plane dc current in a magnetic insulator, confirming theoretical predictions and observing auto-oscillation onset.

Findings

Complete damping compensation at a specific current density.

Detection of a small change in static magnetization at threshold.

Agreement of experimental results with theoretical models.

Abstract

It is demonstrated that the decay time of spin-wave modes existing in a magnetic insulator can be reduced or enhanced by injecting an in-plane dc current, $I_\text{dc}$, in an adjacent normal metal with strong spin-orbit interaction. The demonstration rests upon the measurement of the ferromagnetic resonance linewidth as a function of $I_\text{dc}$ in a 5~$\mu$m diameter YIG(20nm){\textbar}Pt(7nm) disk using a magnetic resonance force microscope (MRFM). Complete compensation of the damping of the fundamental mode is obtained for a current density of $\sim 3 \cdot 10^{11}\text{A.m}^{-2}$, in agreement with theoretical predictions. At this critical threshold the MRFM detects a small change of static magnetization, a behavior consistent with the onset of an auto-oscillation regime.