Antiferromagnetism and the gap of a Mott insulator: Results from analytic continuation of the self-energy

TL;DR

This paper uses analytic continuation of the self-energy to study how antiferromagnetic order affects the spectral properties and gap size of a Mott insulator, revealing an 80% increase in the gap due to antiferromagnetism.

Contribution

It introduces a robust method for estimating the Mott gap via the real part of the continued self-energy within dynamical mean field theory.

Findings

Antiferromagnetism increases the Mott gap by about 80%.

The real part of the self-energy provides a reliable gap estimate.

Analytic continuation methods are validated for spectral analysis.

Abstract

Direct analytic continuation of the self energy is used to determine the effect of antiferromagnetic ordering on the spectral function and optical conductivity of a Mott insulator. Comparison of several methods shows that the most robust estimation of the gap value is obtained by use of the real part of the continued self energy in the quasiparticle equation within the single-site dynamical mean field theory of the two dimensional square lattice Hubbard model, where for U slightly greater than the Mott critical value, antiferromagnetism increases the gap by about 80%.