Incommensurate antiferromagnetic fluctuations in the two-dimensional Hubbard model

TL;DR

This paper investigates antiferromagnetic fluctuations in the 2D Hubbard model, revealing the existence of incommensurate order below a pseudocritical temperature and highlighting the importance of fluctuations beyond mean field.

Contribution

It demonstrates the presence of incommensurate antiferromagnetic order in the 2D Hubbard model using functional renormalization group methods, emphasizing the role of fluctuations.

Findings

Incommensurate order exists below a pseudocritical temperature.

Fluctuations reduce the pseudocritical temperature by approximately 2.5 times.

Incommensurate fluctuations are significant away from half filling.

Abstract

Commensurate and incommensurate antiferromagnetic fluctuations in the two-dimensional repulsive t-t'-Hubbard model are investigated using functional renormalization group equations. For a sufficient deviation from half filling we establish the existence of local incommensurate order below a pseudocritical temperature T_{pc}. Fluctuations not accounted for in the mean field approximation are important--they lower T_{pc} by a factor \approx2.5.