Spin wave spectrum of a disordered double exchange model

TL;DR

This paper investigates how quenched disorder in conduction electrons affects the spin wave spectrum in a double exchange model, revealing gap formation and potential spin-glass behavior due to disorder-induced frustration.

Contribution

It introduces a field theoretical approach using path integrals and replica techniques to derive the ensemble-averaged spin wave dispersion in a disordered double exchange model.

Findings

Spin wave spectrum exhibits gaps at multiples of the Fermi wavenumber due to disorder.

Disorder induces frustration leading to possible spin-glass like behavior.

Results highlight the significant impact of electron disorder on localized spin dynamics.

Abstract

A double exchange model with quenched disorder for conduction electrons is studied by field theoretical methods. By using a path integral formalism and replica techniques based on it, an ensemble-averaged spin wave dispersion of the localized spins is derived. It is shown that the spectrum of the spin wave has gaps at the multiple of the Fermi wavenumber of the conduction electrons in the presence of disorder, and hence, quenched disorder for electrons adds a striking effect to the dynamics of the localized spins. In the strong disorder limit, the present results suggest spin-glass like behavior due to the frustration of the exchange coupling.