Spin Seebeck Effect: Amplification of Spin Waves by Thermal Torque

TL;DR

This paper demonstrates that a transverse temperature gradient can amplify spin-wave packets in YIG films through a thermal torque generated by the spin Seebeck effect, supported by experimental and theoretical analysis.

Contribution

It introduces the concept of amplifying spin waves via thermal torque induced by the spin Seebeck effect, combining experimental observations with a theoretical model.

Findings

Spin-wave amplification observed under temperature gradient

Amplification gain matches theoretical predictions

Thermal torque opposes spin-wave relaxation

Abstract

We observe amplification of spin-wave packets propagating along a film of yttrium iron garnet (YIG) subject to a transverse temperature gradient. The amplification is attributed to a spin-transfer thermal torque created by spin currents generated by means of the spin Seebeck effect that acts on the magnetization and opposes the relaxation. The experimental data are interpreted with a simple theoretical model using spin-wave theory that gives an amplification gain in very good agreement with measurements.