Topological antiferromagnetic phase in a correlated Bernevig-Hughes-Zhang model

TL;DR

This paper investigates the topological properties of antiferromagnetic phases in a correlated topological insulator using dynamical mean field theory, revealing a correlation-stabilized non-trivial AF phase beyond Hartree-Fock predictions.

Contribution

It demonstrates that strong correlations stabilize a topologically non-trivial antiferromagnetic phase, which is not captured by mean-field Hartree-Fock theory.

Findings

Non-trivial AF phase confirmed by spin Chern number calculations

Correlation effects stabilize topological AF phase beyond Hartree-Fock

Counterintuitive stabilization of topological phase by correlations

Abstract

Topological properties of antiferromagnetic phases are studied for a correlated topological band insulator by applying the dynamical mean field theory to an extended Bernevig-Hughes-Zhang model including the Hubbard interaction. The calculation of the magnetic moment and the spin Chern number confirms the existence of a non-trivial antiferromagnetic (AF) phase beyond the Hartree-Fock theory. In particular, we uncover the intriguing fact that the topologically non-trivial AF phase is essentially stabilized by correlation effects but not by the Hartree shifts alone. This counterintuitive effect is demonstrated, through a comparison with the Hartree-Fock results, and should apply for generic topological insulators with strong correlations.