Magnetic Susceptibility of the Double-Exchange Model in the RKKY Limit

TL;DR

This paper investigates the magnetic susceptibility and spin-glass order in the double-exchange model within the RKKY limit, revealing specific temperature-dependent behaviors and phase characteristics using dynamical mean-field theory.

Contribution

It provides a theoretical analysis of the SGL phase in the double-exchange model, deriving explicit relations for the order parameter and susceptibility in the weak-coupling limit.

Findings

The order parameter q follows a quadratic temperature dependence, q=M(T/Tsg)^2.

The magnetic susceptibility exhibits a cusp at the transition temperature Tsg.

The susceptibility remains nonzero as temperature approaches zero.

Abstract

The magnetic susceptibility and Edwards-Anderson order parameter q of the spin-glass-like (SGL) phase of the double-exchange model are evaluated in the weak-coupling or RKKY limit. Dynamical mean-field theory is used to show that q=M(T/Tsg)^2, where M is the classical Brillouin function and Tsg is the SGL transition temperature. The correlation length of the SGL phase is determined by a correlation parameter Q that maximizes Tsg and minimizes the free energy. The magnetic susceptibility has a cusp at Tsg and reaches a nonzero value as T goes to zero.