Ground state and spectral properties across a Charge Density Wave transition in a triangular-lattice spinless Fermion model

TL;DR

This paper investigates the ground state and excitation spectra of a spinless fermion system on a triangular lattice undergoing a charge density wave transition, revealing how spectral properties change across the transition.

Contribution

It introduces a combined use of series expansion and mean-field theory to analyze the phase transition and spectral changes in a 1/3-filled triangular-lattice fermion model.

Findings

First-order transition at zero sublattice potential

Transition becomes continuous with increasing sublattice potential

Spectral properties show dramatic changes near phase transition

Abstract

We study ground state properties and particle excitation spectra across a commensurate charge density wave transition in a system of strongly interacting fermions, using series expansion methods and mean-field theory. We consider a 1/3-filled system of spinless fermions on a triangular-lattice, with hopping parameter $t$, nearest-neighbor repulsion $V$, and a sublattice dependent chemical potential $\mu_s$. The phase transition is found to be first order for $\mu_s=0$, but becomes continuous with increasing $\mu_s$. The particle and hole excitation spectra exhibit dramatic changes in the vicinity of the phase transitions and in the charge-density wave ordered phase. We discuss the relevance of this study to the Pinball Fermi liquid phase postulated theoretically in earlier studies as well as to various strongly correlated triangular-lattice materials.