Fermion kinetics in the Falicov-Kimball limit of the three-band Emery model

TL;DR

This paper models fermion behavior in a simplified three-band Emery model using a Falicov-Kimball approach, revealing entropy plateaus, anomalous thermopower, and non-Fermi liquid features through an effective free-energy analysis.

Contribution

It introduces a novel reduction of the three-band Emery model to a Falicov-Kimball type, enabling exact evaluation of thermodynamic properties.

Findings

Entropy plateau due to charge correlations at low hopping overlap

Anomalous thermopower susceptibility with opposite sign to density of states

Discussion of heat capacity and non-Fermi liquid behavior

Abstract

The three-band Emery model is reduced to a single-particle quantum model of Falicov-Kimball type, by allowing only up-spins to hop, and forbidding double occupation by projection. It is used to study the effects of geometric obstruction on mobile fermions in thermodynamic equilibrium. For low hopping overlap, there appears a plateau in the entropy, due to charge correlations, and related to real-space disorder. For large overlap, the equilibrium thermopower susceptibility remains anomalous, with a sign opposite to the one predicted from the single-particle density of states. The heat capacity and non-Fermi liquid response are discussed in the context of similar results in the literature. All results are obtained by evaluation of an effective single-particle free-energy operator in closed form. The method to obtain this operator is described in detail.