Correlated spinless fermions on the honeycomb lattice revisited

TL;DR

This paper uses the functional renormalization group to study the phase diagram of spinless fermions on a honeycomb lattice, revealing suppression of topological Mott insulator phases and highlighting competing charge orderings.

Contribution

It provides a new analysis of the extended Hubbard model using fRG, clarifying the stability of topological phases and charge orderings compared to previous numerical methods.

Findings

Suppression of topological Mott insulator by fermionic fluctuations

Phase diagram showing competition among charge orderings

fRG results align with some previous studies but challenge others

Abstract

We investigate the quantum many-body instabilities of the extended Hubbard model for spinless fermions on the honeycomb lattice with repulsive nearest-neighbor and 2nd nearest-neighbor density-density interactions. Recent exact diagonalization and infinite density matrix renormalization group results suggest that a putative topological Mott insulator phase driven by the 2nd nearest-neighbor repulsion is suppressed, while other numerically exact approaches support the topological Mott insulator scenario. In the present work, we employ the functional renormalization group (fRG) for correlated fermionic systems. Our fRG results hint at a strong suppression of the scattering processes stabilizing the topological Mott insulator. From analyzing the effects of fermionic fluctuations, we obtain a phase diagram which is the result of the competition of various charge ordering instabilities.