Mobile Dopants in Inhomogeneous Superconductors

TL;DR

This paper investigates how mobile impurities with varying local BCS interactions influence superconductivity, revealing impurity attraction leads to condensation and examining impurity distributions near interfaces.

Contribution

It introduces a model for mobile impurities with different BCS interactions and analyzes their tendency to form condensed states in inhomogeneous superconductors.

Findings

Impurities tend to form condensed states due to mutual attraction.

The distribution of impurities near interfaces affects local superconducting properties.

Mobile impurities with different interactions modify the superconductor's inhomogeneity.

Abstract

We consider a superconductor hosting mobile impurities, which locally change the superconducting transition temperature. The BCS interaction at the impurity is different both in magnitude and in sign from the BCS interaction in the bulk. It is shown that due to the attraction between impurities, they tend to form more condensed state. We also consider the distribution of mobile impurities with local BCS attraction or repulsion at the vicinity of the superconductor-normal metal interface.