Parity-breaking phases of spin-orbit-coupled metals with gyrotropic, ferroelectric and multipolar orders

TL;DR

This paper investigates how spin-orbit-coupled metals with inversion symmetry can develop various parity-breaking phases, leading to Fermi surface deformations and unique optical properties, with implications for quantum materials like pyrochlore oxides.

Contribution

It derives the general form of interaction functions in spin-orbit-coupled metals and identifies new parity-breaking phases with distinct symmetry properties and experimental signatures.

Findings

Identification of time-reversal-invariant, parity-breaking phases with deformed, spin-split Fermi surfaces.

Discovery of gyrotropic, ferroelectric, and multipolar orders in these phases.

Connection of theoretical phases to experimental observations in pyrochlore oxides.

Abstract

We study Fermi liquid instabilities in spin-orbit-coupled metals with inversion symmetry. By introducing a canonical basis for the doubly degenerate Bloch bands in momentum space, we derive the general form of interaction functions. A variety of time-reversal-invariant, parity-breaking phases is found, whose Fermi surface is spontaneously deformed and spin-split. In terms of symmetry, these phases possess gyrotropic, ferroelectric and multipolar orders. The ferroelectric and multipolar phases are accompanied by structural distortions, from which the electronic orders can be identified. The gyrotropic phase exhibits a unique nonlinear optical property. Based on recent experiments, we identify several interesting quantum materials including pyrochlore oxides, which show evidence of these parity breaking orders.