Absence of broken inversion symmetry phase of electrons in bilayer graphene under charge density fluctuations

TL;DR

This study investigates whether a gapped broken inversion symmetry phase exists in bilayer graphene considering charge density fluctuations, finding that such fluctuations can destroy the phase predicted by mean-field theory.

Contribution

The paper demonstrates that charge-density fluctuations negate the existence of the GBISP in bilayer graphene, challenging previous mean-field predictions and providing a numerical method for electron self-energy calculations.

Findings

Charge-density fluctuations destroy the GBISP predicted by mean-field theory.

A numerical algorithm for electron self-energy with long-range Coulomb interaction is developed.

The GBISP is not stable at finite temperature and carrier concentration when fluctuations are considered.

Abstract

On a lattice model, we study the possibility of existence of gapped broken inversion symmetry phase (GBISP) of electrons with long-range Coulomb interaction in bilayer graphene using both self-consistent Hartree-Fock approximation (SCHFA) and the renormalized-ring-diagram approximation (RRDA). RRDA takes into account the charge-density fluctuations beyond the mean field. While GBISP at low temperature and low carrier concentration is predicted by SCHFA, we show here the state can be destroyed by the charge-density fluctuations. We also present a numerical algorithm for calculating the self-energy of electrons with the singular long-range Coulomb interaction on the lattice model.