Frequency dependent conductivity of vortex cores in type II superconductors

TL;DR

This paper investigates the frequency-dependent conductivity of vortex cores in type II superconductors, emphasizing the role of pinning in revealing resonant dipole transitions relevant to optical experiments.

Contribution

It provides a microscopic calculation of vortex response including pinning effects, clarifying the conditions for observing dipole resonances in high Tc superconductors.

Findings

Resonant dipole transition is absent without pinning due to translation invariance.

Pinning restores the dipole resonance, highlighting its experimental significance.

The study connects microscopic vortex response to optical transmission observations.

Abstract

This paper is relevant to the recent optical transmission experiments of Karrai et al. for vortices in high Tc superconductors. We begin with a substantial review and introduction. The microscopic response of vortices is calculated from the Bogoliubov-deGennes equation, including an equation of motion and conductivity. We find that the expected resonant dipole transtition is not present because of translation invariance. We consider the effect of pinning and show that in the presence of pinning one recovers the dipole resonance. Thus we conclude that pinning may play an important role in the experiment.