Spectral properties of locally correlated electrons in a BCS superconductor

TL;DR

This paper investigates the spectral behavior of a locally correlated impurity in a BCS superconductor using NRG, revealing details about Andreev states and phase diagrams relevant for superconducting DMFT.

Contribution

It provides a comprehensive analysis of the spectral properties and phase diagrams of a correlated impurity in a superconducting medium using NRG, including effects of particle-hole symmetry.

Findings

Position and weight of Andreev bound states characterized

Phase diagrams of ground state regimes mapped

Spectral responses elucidated for various parameters

Abstract

We present a detailed study of the spectral properties of a locally correlated site embedded in a BCS superconducting medium. To this end the Anderson impurity model with superconducting bath is analysed by numerical renormalisation group (NRG) calculations. We calculate one and two-particle dynamic response function to elucidate the spectral excitation and the nature of the ground state for different parameter regimes with and without particle-hole symmetry. The position and weight of the Andreev bound states is given for all relevant parameters. We also present phase diagrams for the different ground state parameter regimes. This work is also relevant for dynamical mean field theory extensions with superconducting symmetry breaking.