Charge and magnetic order in the 2D Falicov-Kimball model with Hund coupling at finite temperatures

TL;DR

This paper analyzes the finite temperature charge and magnetic order in a 2D Falicov-Kimball model with Hund coupling, identifying phase transitions and how transition temperatures depend on interaction parameters.

Contribution

It introduces an approximate scheme to estimate free energies of different phases in the model, revealing phase transition behaviors at finite temperatures.

Findings

Transition temperature between SCO and CO is much lower than between CO and NO.

Maximum transition temperatures occur at similar coupling constant values.

Phase transitions depend on on-site interaction parameters.

Abstract

We perform a simplified analysis of finite temperature properties of the generalized Falicov-Kimball model with Hund coupling. The model is studied on the square lattice for fixed values of \emph{f-electron} and \emph{d-electron} densities $\rho_f=1/2$, $\rho_d=1$. Using an approxiamte scheme we estimated free energies of the following three phases: the charge and spin ordered (SCO), the charge ordered (CO) and the non-ordered (NO). Comparing the free energies we detected phase transitions and found how the transition temperatures depend on the on-site interaction parameters. It appears, that the transition temperture between SCO and CO is much lower than between CO and NO, but their maximum values are attained at values of coupling constants very close to each other.