Deformation of Fermi Surface Due to Antiferromagnetic Correlation

TL;DR

This paper studies how antiferromagnetic correlations in a 2D Hubbard model cause the Fermi surface to deform and develop nesting features as the Coulomb interaction approaches the critical value for antiferromagnetic order.

Contribution

It demonstrates how increasing Coulomb interaction enhances AF correlations and deforms the Fermi surface, revealing nesting tendencies near the critical interaction strength.

Findings

AF correlation length increases near critical U

Fermi surface becomes deformed with nesting tendency

Shape changes are driven by AF correlations

Abstract

It is investigated, on the basis of the fluctuation exchange approximation, how the shape of the Fermi surface is modified in two-dimensional $t-t'-U$ Hubbard model at half filling as strength of the onsite Coulomb interaction $U$ is increased. The antiferromagnetic (AF) correlation length is shown to be enhanced as the Coulomb interaction get closer to the critical value $U_{\rm c}$ for the onset AF order. At the same time, the shape of the renormalized Fermi surface is deformed showing the tendency of nesting near $U_{\rm c}$.