Control of Yu-Shiba-Rusinov States through a Bosonic Mode

TL;DR

This paper explores how coupling a bosonic mode to a magnetic impurity in a superconductor can control Yu-Shiba-Rusinov states, revealing new odd-parity states and tunable properties via phononic or photonic interactions.

Contribution

It predicts the emergence of additional odd-parity YSR states due to a bosonic mode coupling, expanding understanding of impurity states in superconductors.

Findings

Bosonic mode coupling induces additional YSR states.

The exchange couplings depend on the bosonic mode state.

Control over YSR states via phononic or photonic means is possible.

Abstract

We investigate the impact of a bosonic degree of freedom on Yu-Shiba-Rusinov (YSR) states emerging from a magnetic impurity in a conventional superconductor. Starting from the Anderson impurity model, we predict that an additional p-wave conduction band channel opens up if a bosonic mode is coupled to the tunnelling between impurity and host, which implies an additional pair of odd-parity YSR states. The bosonic mode can be a vibrational mode or the electromagnetic field in a cavity. The exchange couplings in the two channels depend sensitively on the state of the bosonic mode (ground state, few quanta or classically driven Floquet state), which opens possibilities for phononics or photonics control of such systems, with a rich variety of ground and excited states.