Chiral Optical Absorption by a Vortex in p_x \pm i p_y-Wave Superconductor

TL;DR

This paper theoretically investigates how chiral optical absorption by vortices in p_x ± i p_y-wave superconductors can reveal the superconducting state's orbital symmetry and vortex winding, providing a potential experimental detection method.

Contribution

It introduces a theoretical framework for chiral optical absorption in p_x ± i p_y-wave superconductors and suggests its use to detect orbital-dependent superconductivity in Sr_2 Ru O_4.

Findings

Optical absorption depends on vortex winding and shows a low-energy peak.

Dichroism occurs in single Fermi surface superconductivity.

Multiple Fermi surfaces can suppress dichroism.

Abstract

The chiral optical absorption by a single vortex in a p_x \pm i p_y-wave superconductor is studied theoretically. The p_x \pm i p_y-wave state was recently suggested as the symmetry of the order parameter of Sr_2 Ru O_4 superconductor. Due to the violation of time reversal symmetry, there are two types of vortices whose winding orientation is the same or opposite to the angular momentum of the Cooper pair. In a real material domains with p_x \pm i p_y-wave states are expected. However, optical absorption of circular polarized light depends only on the winding of the vortex and has a low energy absorption peak which results in dichroism. Dichroism occurs if superconductivity is realized on a single Fermi surface sheet. However, in the case of several Fermi surface sheets dichroism may disappear, if the both types of carriers are present, electron-like and hole-like. Therefore chiral optical absorption is a possible experiment to detect the orbital dependent superconductivity which was suggested as the superconducting state of Sr_2 Ru O_4.