Theory of the Lightly Doped Mott Insulator

TL;DR

This paper develops a theoretical framework for the Hubbard model in the large U/t limit with low doping, revealing elliptical hole pockets and the dominance of longer-range hopping due to antiferromagnetic correlations.

Contribution

It introduces a novel theory for the lightly doped Mott insulator that captures Fermi surface shape and hopping effects without broken symmetry.

Findings

Fermi surface consists of elliptical hole pockets near (pi/2, pi/2).

Volume of pockets proportional to hole concentration.

Second and third nearest neighbor hopping dominate dispersion.

Abstract

A theory for the Hubbard model appropriate in the limit of large U/t, small doping away from half-filling and short-ranged antiferromagnetic spin correlations is presented. Despite the absence of any broken symmetry the Fermi surface takes the form of elliptical hole pockets centered near (pi/2,pi/2) with a volume proportional to the hole concentration. Short range antiferromagnetic correlations render the nearest neighbor hopping almost ineffective so that only second or third nearest neighbor hopping contributes appreciably to the dispersion relation.