Quantum Interference between Impurities: Creating Novel Many-Body States in s-wave Superconductors

TL;DR

This paper explores how quantum interference between multiple magnetic impurities in s-wave superconductors creates new many-body bound states, with tunable properties influenced by impurity arrangements and spins.

Contribution

It introduces a novel mechanism for generating and controlling many-body states in superconductors via impurity interference effects.

Findings

Impurity interference leads to new bound states in superconductors.

Adjusting impurity positions or spins alters quantum numbers and spatial properties.

Superconductor spin polarization undergoes multiple local crossovers.

Abstract

We demonstrate that quantum interference of electronic waves that are scattered by multiple magnetic impurities in an s-wave superconductor gives rise to novel bound states. We predict that by varying the inter-impurity distance or the relative angle between the impurity spins, the states' quantum numbers, as well as their distinct frequency and spatial dependencies, can be altered. Finally, we show that the superconductor can be driven through multiple local crossovers in which its spin polarization, $<s_z >$, changes between $<s_z >=0, 1/2$ and 1.