Competition between Pomeranchuk instabilities in the nematic and hexatic channels in a two-dimensional spinless Fermi fluid

TL;DR

This paper investigates the competition between nematic and hexatic phases in a two-dimensional spinless Fermi fluid, revealing a complex phase diagram with a bicritical point and unique dissipative modes at criticality.

Contribution

It introduces a detailed phase diagram for nematic and hexatic phases, identifying a bicritical point and analyzing the low energy dissipative modes governing the system.

Findings

Identification of a bicritical point where different phase transition lines meet.

Discovery of a dissipative cubic mode governing low energy dynamics.

Strong dynamical coupling causes nematic and hexatic fluctuations to become indistinguishable at criticality.

Abstract

We study the competition between the nematic and the hexatic phases of a two-dimensional spinless Fermi fluid near Pomeranchuk instabilities. We show that the general phase diagram of this theory contains a bicritical point where two second order lines and a first order nematic/hexatic phase transition meet together. We found that at criticality, and deep inside the associated symmetry broken phases, the low energy theory is governed by a dissipative cubic mode, even near the bicritical point where nematic and hexatic fluctuations cannot be distinguished due to very strong dynamical couplings.