Spin Wave Theory of Double Exchange Ferromagnets

TL;DR

This paper develops a 1/S spin-wave theory for double exchange ferromagnets at zero temperature, revealing magnon-electron scattering causes spin wave damping and discussing implications for colossal magnetoresistance materials.

Contribution

It introduces a detailed spin-wave expansion for double exchange ferromagnets, including damping effects from magnon-electron interactions, challenging previous assumptions.

Findings

Magnon-electron scattering leads to spin wave damping.

The theory predicts specific momentum-dependent behaviors.

Implications for experimental studies of colossal magnetoresistance.

Abstract

We construct the 1/S spin-wave expansion for double exchange ferromagnets at T=0. It is assumed that the value of Hund's rule coupling, J_H, is sufficiently large, resulting in a fully saturated, ferromagnetic half-metallic ground state. We evaluate corrections to the magnon dispersion law, and we also find that, in contrast to earlier statements in the literature, magnon-electron scattering does give rise to spin wave damping. We analyse the momentum dependence of these quantities and discuss the experimental implications for colossal magnetoresistance compounds.