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

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.