Natural optical activity of metals

TL;DR

This paper derives the electromagnetic response of noncentrosymmetric metals, revealing how their optical activity and Kerr rotation depend on fundamental constants and spin-orbit interactions, applicable in both normal and superconducting states.

Contribution

It provides a theoretical derivation of the conductivity tensor including natural optical activity in metals with broken inversion symmetry, linking optical effects to fundamental physical parameters.

Findings

Derived the current response tensor with off-diagonal terms causing optical activity.

Calculated Kerr rotation in terms of fine-structure constant and spin-orbit band splitting.

Showed the response applies to both normal and superconducting states.

Abstract

We derive the current response of noncentrosymmetric metal in normal and in superconducting states to the electromagnetic field with finite frequency and wave vector. The conductivity tensor is found contains the linear in wave vector off diagonal part generating natural optical activity. The Kerr rotation of polarization of light reflected from the metal surface is calculated. Its value is expressed through the fine-structure constant and the ratio of light frequency to the band splitting due to the spin-orbit interaction.