Correlated Dirac semimetal by periodized cluster dynamical mean-field theory

TL;DR

This paper applies periodized cluster dynamical mean-field theory to the Hubbard model on a honeycomb lattice, revealing a transition from a correlated Dirac semimetal to an antiferromagnetic insulator without an intervening spin liquid phase.

Contribution

It introduces the PCDMFT method with exact diagonalization to accurately study the Hubbard model, resolving issues of symmetry breaking and spurious phases in previous methods.

Findings

Identifies a first-order quantum phase transition from semimetal to insulator.

Shows PCDMFT restores translation symmetry and avoids spurious insulating phases.

Finds no evidence of a spin liquid phase between the two states.

Abstract

The periodized cluster dynamical mean-field theory (PCDMFT) combined with exact diagonalization as impurity solver has been applied to the half-filled standard Hubbard model on the honeycomb lattice. A correlated Dirac semimetal is found for weak interactions and it transforms into an antiferromagnetic insulating phase for strong interactions via a first-order quantum phase transition, not intervened by a spin liquid phase in between. In this application, the PCDMFT introduces the partial translation symmetry, but cures well the problem due to the translation symmetry breaking in the cluster dynamical mean-field theory studies for the same model, which give rise to a spurious insulating phase in the weakly interacting region.