Quantum interference between non-magnetic impurities in d_x2-y2-wave superconductors

TL;DR

This paper investigates how quantum interference from non-magnetic impurities affects electronic states in d_x2-y2-wave superconductors, revealing that impurity arrangement influences resonance states and can help identify superconductor symmetry.

Contribution

It demonstrates that impurity interference patterns depend on impurity placement and orientation, offering a new method to determine the symmetry of unconventional superconductors.

Findings

Resonance states vary with impurity distance and orientation.

Quantum interference patterns reveal superconducting gap symmetry.

Impurity effects can be used as a diagnostic tool for superconductor classification.

Abstract

We study quantum interference of electronic waves that are scattered by multiple non-magnetic impurities in a d_x2-y2-wave superconductor. We show that the number of resonance states in the density-of-states (DOS), as well as their frequency and spatial dependence change significantly as the distance between the impurities or their orientation relative to the crystal lattice is varied. Since the latter effect arises from the momentum dependence of the superconducting gap, we argue that quantum interference is a novel tool to identify the symmetry of unconventional superconductors.