Supercurrent Distribution in Real-Space and Anomalous Paramagnetic Response in a Superconducting Quasicrystal

TL;DR

This paper investigates the distribution of supercurrents in a two-dimensional quasiperiodic superconductor, revealing unusual paramagnetic behaviors and current violations due to the quasiperiodic structure.

Contribution

It introduces a theoretical analysis of supercurrent behavior in a quasiperiodic superconductor using the Bogoliubov-de Gennes framework, highlighting anomalous paramagnetic responses.

Findings

Diamagnetic current violates local current conservation.

Paramagnetic current exhibits exotic orientations, including transverse and reversed flows.

Supercurrent distribution depends on electron density, temperature, and vector potential angle.

Abstract

We theoretically study the real-space distribution of the supercurrent that flows under a uniform vector potential in a two-dimensional quasiperiodic structure. This is done by considering the attractive Hubbard model on the quasiperiodic Ammann-Beenker structure and studying the superconducting phase within the Bogoliubov-de Gennes mean-field theory. Decomposing the local supercurrent into the paramagnetic and diamagnetic components, we numerically investigate their dependencies on average electron density, temperature, and the angle of the applied vector potential. We find that the diamagnetic current locally violates the current conservation law, necessitating compensation from the paramagnetic current, even at zero temperature. The paramagnetic current shows exotic behaviors in the quasiperiodic structure, such as local currents which are oriented transversally or reversely to that of the applied vector potential.