Doping change and distortion effect on double-exchange ferromagnetism

TL;DR

This paper investigates how doping and lattice distortions influence double-exchange ferromagnetism, revealing a complex phase diagram with competing magnetic and charge-ordered phases using dynamical mean-field theory.

Contribution

It introduces a simplified model incorporating distortion effects via Falicov-Kimball interaction and provides an exact calculation of susceptibilities, revealing new insights into phase competition.

Findings

Ferromagnetism competes with disorder-order transitions.

Multiple long-range ordered phases coexist with ferromagnetism.

A rich phase diagram dependent on doping and distortion.

Abstract

Doping change and distortion effect on the double-exchange ferromagnetism are studied within a simplified double-exchange model. The presence of distortion is modelled by introducing the Falicov-Kimball interaction between itinerant electrons and classical variables. By employing the dynamical mean-field theory the charge and spin susceptibility are exactly calculated. It is found that there is a competition between the double-exchange induced ferromagnetism and disorder-order transition. At low temperature various long-range order phases such as charge ordered and segregated phases coexist with ferromagnetism depending on doping and distortion. A rich phase diagram is obtained.