Spontaneous breaking of four-fold rotational symmetry in two-dimensional electron systems as a topological phase transition

TL;DR

This paper investigates how four-fold rotational symmetry breaking in 2D electron systems occurs via a topological phase transition driven by antiferromagnetic fluctuations, revealing highly anisotropic spectral features.

Contribution

It introduces an extended Fermi liquid framework to explain symmetry breaking as a topological transition, contrasting with mean-field predictions.

Findings

Symmetry breaking is linked to a topological phase transition.

The spectral structure is highly anisotropic near saddle points.

Antiferromagnetic fluctuations play a key role in the transition.

Abstract

Motivated by recent observations of $C_4$ symmetry breaking in strongly correlated two-dimensional electron systems on a square lattice, we analyze this phenomenon within an extended Fermi liquid approach. It is found that the symmetry violation is triggered by a continuous topological phase transition associated with exchange of antiferromagnetic fluctuations. In contrast to predictions of mean-field theory, the structure of a part of the single-particle spectrum violating $C_4$ symmetry is found to be highly anisotropic, with a peak located in the vicinity of saddle points.