Relation between Vortex Pinning Energy and Anderson's Theorem

TL;DR

This paper explores how vortex pinning energy in type-II superconductors is affected by Anderson's theorem, focusing on unconventional superconductors and the influence of chirality in chiral p-wave superconductors.

Contribution

It reveals the enhancement of vortex pinning energy due to pair-breaking effects and the impact of chirality on vortex pinning in chiral p-wave superconductors.

Findings

Vortex pinning energy is enhanced in unconventional superconductors due to pair-breaking effects.

Chirality influences vortex pinning energy in chiral p-wave superconductors.

Local applicability of Anderson's theorem varies with vortex core properties.

Abstract

We discuss the elementary vortex pinning in type-II superconductors in connection with the Anderson's theorem for nonmagnetic impurities. We address the following two issues. One is an enhancement of the vortex pinning energy in the unconventional superconductors. This enhancement comes from the pair-breaking effect of a nonmagnetic defect as the pinning center far away from the vortex core (i.e., the pair-breaking effect due to the non-applicability of the Anderson's theorem in the unconventional superconductors). The other is an effect of the chirality on the vortex pinning energy in a chiral p-wave superconductor. The vortex pinning energy depends on the chirality. This is related to the cancellation of the angular momentum between the vorticity and chirality in a chiral p-wave vortex core, resulting in local applicability of the Anderson's theorem (or local recovery of the Anderson's theorem) inside the vortex core.