Linear-response theory of spin Seebeck effect in ferromagnetic insulators

TL;DR

This paper develops a linear response theoretical framework to understand the spin Seebeck effect in ferromagnetic insulators, emphasizing magnon contributions, and successfully explains experimental observations in yttrium iron garnet.

Contribution

It introduces a linear response approach focusing on magnons to quantitatively describe the spin Seebeck effect in ferromagnetic insulators.

Findings

Qualitative and quantitative agreement with experimental data

Magnons are key carriers in the spin Seebeck effect

Provides a theoretical basis for future spin caloritronics research

Abstract

We formulate a linear response theory of the spin Seebeck effect, i.e., a spin voltage generation from heat current flowing in a ferromagnet. Our approach focuses on the collective magnetic excitation of spins, i.e., magnons. We show that the linear-response formulation provides us with a qualitative as well as quantitative understanding of the spin Seebeck effect observed in a prototypical magnet, yttrium iron garnet.