Mott Transitions in the 2D Half-Filled Hubbard Model: Correlator Projection Method with Projective Dynamical Mean-Field Approximation

TL;DR

This paper introduces an improved correlator projection method combined with a dynamical mean-field approximation to study Mott transitions in the 2D Hubbard model, revealing complex phase behavior and spectral features.

Contribution

It develops a systematic higher-order approximation that incorporates spatial correlations, extending the dynamical mean-field approach for the 2D Hubbard model.

Findings

First-order Mott transition surface with a finite-temperature critical end curve

Antiferromagnetic correlations significantly modify single-particle spectra

Shadow bands and flat dispersions observed similar to high-T_c cuprates

Abstract

The 2D half-filled Hubbard model is studied by a nonperturbative analytic theory of correlator projection. The original dynamical mean-field approximation (DMFA) is reproduced at the first-order projection and then improved by systematic inclusion of spatial correlations at higher orders. A geometrical frustration induces a first-order Mott transition surface with a finite-temperature critical end curve. Growth of antiferromagnetic correlations gives single-particle spectra strongly modified from DMFA with shadow bands and flat dispersions observed in high-T_c cuprates.