Spin wave excitation in magnetic insulators by spin-transfer torque

TL;DR

This paper investigates how spin-transfer torque can excite surface spin waves in magnetic insulators, revealing that surface anisotropy significantly lowers the critical current needed for excitation and boosts the power of magnetization dynamics.

Contribution

It predicts the preferential excitation of surface spin waves due to easy-axis surface anisotropy and quantifies how surface properties influence critical current and excitation efficiency.

Findings

Surface spin waves are preferentially excited by spin-transfer torque.

Critical current is inversely proportional to penetration depth and surface anisotropy.

Surface modes reduce the critical current and increase excitation power.

Abstract

We study the excitation of spin waves in magnetic insulators by the current-induced spin-transfer torque. We predict preferential excitation of surface spin waves induced by an easy-axis surface anisotropy with critical current inversely proportional to the penetration depth and surface anisotropy. The surface modes strongly reduce the critical current and enhance the excitation power of the current-induced magnetization dynamics.