Propagation of Thermally Induced Magnonic Spin Currents

TL;DR

This study explores how thermally induced magnon spin currents propagate in ferromagnetic insulators, analyzing factors affecting their length and frequency distribution using atomistic simulations.

Contribution

It introduces an atomistic spin model framework to analyze magnon propagation under thermal gradients, including effects of anisotropy and damping.

Findings

Propagation length of a few micrometers for low damping materials

Frequency distribution influenced by anisotropy and damping

Exchange-driven magnons dominate propagation in soft ferromagnets

Abstract

The propagation of magnons in temperature gradients is investigated within the framework of an atomistic spin model with the stochastic Landau-Lifshitz-Gilbert equation as underlying equation of motion. We analyze the magnon accumulation, the magnon temperature profile as well as the propagation length of the excited magnons. The frequency distribution of the generated magnons is investigated in order to derive an expression for the influence of the anisotropy and the damping parameter on the magnon propagation length. For soft ferromagnetic insulators with low damping a propagation length in the range of some $\mu$m can be expected for exchange driven magnons.