Nematic Fermi Fluids in Condensed Matter Physics

TL;DR

This paper reviews the concept of electron nematic phases in condensed matter, highlighting experimental evidence from quantum Hall systems, Sr3Ru2O7, and potential indications in high-temperature superconductors.

Contribution

It provides a comprehensive review of the theoretical background and experimental discoveries of electron nematic phases across various materials.

Findings

Electron nematic phases confirmed in quantum Hall systems and Sr3Ru2O7.

Evidence suggests possible nematic order in cuprate and Fe-based superconductors.

Theoretical understanding of nematic order in correlated electron fluids is summarized.

Abstract

Correlated electron fluids can exhibit a startling array of complex phases, among which one of the more surprising is the electron nematic, a translationally invariant metallic phase with a spontaneously generated spatial anisotropy. Classical nematics generally occur in liquids of rod-like molecules; given that electrons are point-like, the initial theoretical motivation for contemplating electron nematics came from thinking of the electron fluid as a quantum melted electron crystal, rather than a strongly interacting descendent of a Fermi gas. That such phases exist in nature was established by dramatic transport experiments in ultra-clean quantum Hall systems in 1999 and in Sr3Ru2O7 in a strong magnetic field in 2007. In this paper, we briefly review the theoretical considerations governing nematic order, summarize the quantum Hall and Sr3Ru2O7 experiments that unambiguously establish the existence of this phase, and survey some of the current evidence for such a phase in the cuprate and Fe-based high temperature superconductors.