Strong-Coupling Expansion for the Hubbard Model

TL;DR

This paper introduces a strong-coupling expansion method for the Hubbard model applicable in any dimension, successfully capturing key phenomena like the Mott transition and antiferromagnetic correlations, with predictions relevant to experimental observations.

Contribution

It presents a novel strong-coupling expansion technique for correlated electron models, demonstrating its effectiveness in describing the Hubbard model and related phenomena.

Findings

Third order expansion captures Mott transition and antiferromagnetic correlations

Method agrees with numerical results in one dimension

Predicts increased photoemission signals with temperature in certain materials

Abstract

A strong-coupling expansion for models of correlated electrons in any dimension is presented. The method is applied to the Hubbard model in $d$ dimensions and compared with numerical results in $d=1$. Third order expansion of the Green function suffices to exhibit both the Mott metal-insulator transition and a low-temperature regime where antiferromagnetic correlations are strong. It is predicted that some of the weak photoemission signals observed in one-dimensional systems such as $SrCuO_2$ should become stronger as temperature increases away from the spin-charge separated state.