Imperfect nanorings with superconducting correlations

TL;DR

This paper investigates how impurities and electron interactions influence the properties of nanoscopic superconducting rings using numerical methods, revealing the competition between pairing and density wave formation.

Contribution

It introduces a combined numerical approach to analyze impurity effects in nanorings with superconducting correlations, highlighting impurity configuration impacts.

Findings

Impurities act as pinning centers for density waves.

The properties depend on the competition between pairing and density wave tendencies.

Impurity configuration significantly influences system behavior.

Abstract

The properties of nanoscopic rings with electronic correlations and impurities are analyzed numerically by means of two complementary methods. Namely, we perform exact diagonalization of systems up to several lattice sites and Bogoliubov-de Gennes-equations studies of systems consisting of a few hundred sites. We demonstrate how the properties of the systems are affected by various configurations of impurities for both repulsive and attractive electron-electron interactions. In the case of attractive interaction we show that the nanoscopic properties are mainly determined by the competition between tendencies toward pairing and formation of the density waves. Since the impurities act as pinning centers for the density waves, their configuration determines the result of this competition.