Optical gyrotropy in quadrupolar Kondo systems

TL;DR

This paper investigates how quadrupolar order in intermetallic systems influences conduction electrons, revealing a nontrivial Berry curvature that causes optical gyrotropy and potential observable Faraday rotation effects.

Contribution

It demonstrates that quadrupolar order can induce Berry curvature in conduction bands, leading to optical gyrotropy in Kondo systems, a novel insight into their electronic properties.

Findings

Quadrupolar order induces Berry curvature in conduction electrons.

Optical gyrotropic response estimated for PrPb3.

Potential for observable Faraday rotation in thin films.

Abstract

Recent experiments point to a variety of intermetallic systems which exhibit exotic quadrupolar orders driven by the Kondo coupling between conduction electrons and localized quadrupolar degrees of freedom. Using a Luttinger k.p Hamiltonian for the conduction electrons, we study the impact of such quadrupolar order on their energies and wave functions. We discover that such quadrupolar orders can induce a nontrivial Berry curvature for the conduction electron bands, leading to a nonvanishing optical gyrotropic effect. We estimate the magnitude of the gyrotropic response in a candidate quadrupolar material, PrPb3, and discuss the resulting Faraday rotation in thin films.