Nematic phase in a two-dimensional Hubbard model at weak coupling and finite temperature

TL;DR

This study uses self-consistent renormalized perturbation theory to explore nematic phases in a 2D Hubbard model at finite temperature, revealing temperature-dependent nematic order and its competition with superconductivity.

Contribution

It demonstrates the emergence of a nematic phase at finite temperature due to interactions in the Hubbard model, highlighting the role of Van Hove points and phase competition.

Findings

Maximal nematic order occurs at non-zero temperature.

Transitions between phases are first-order.

Nematic phase arises from interaction-driven symmetry breaking.

Abstract

We apply the self-consistent renormalized perturbation theory to the Hubbard model on the square lattice, at finite temperatures in order to study the evolution of the Fermi-surface (FS) as a function of temperature and doping. Previously, a nematic phase for the same model has been reported to appear at weak coupling near a Lifshitz transition from closed to open FS at zero temperature where the self-consistent renormalized perturbation theory was shown to be sensitive to small deformations of the FS. We find that the competition with the superconducting order leads to a maximal nematic order appearing at non-zero temperature. We explicitly observe the two competing phases near the onset of nematic instability and, by comparing the grand canonical potentials, we find that the transitions are first-order. We explain the origin of the interaction-driven spontaneous symmetry breaking to a nematic phase in a system with several symmetry-related Van Hove points and discuss the required conditions.