Thermodynamic Consistency of the Dynamical Mean-Field Theory of the Double-Exchange Model

TL;DR

This paper demonstrates that the dynamical mean-field theory applied to the double-exchange model remains thermodynamically consistent despite the failure of diagrammatic perturbation theory, verified through magnetic susceptibility and Curie temperature calculations.

Contribution

It proves the thermodynamic consistency of the DMFT for the double-exchange model, even when diagrammatic perturbation theory fails, by confirming Phi-derivability and consistency in thermodynamic properties.

Findings

Thermodynamic consistency is maintained in DMFT for the double-exchange model.

Magnetic susceptibility and Curie temperature are accurately evaluated.

The theory remains Phi-derivable despite perturbation theory failures.

Abstract

Although diagrammatic perturbation theory fails for the dynamical-mean field theory of the double-exchange model, the theory is nevertheless Phi-derivable and hence thermodynamically consistent, meaning that the same thermodynamic properties are obtained from either the partition function or the Green's function. We verify this consistency by evaluating the magnetic susceptibility and Curie temperature for any Hund's coupling.