Effect of disorder on superconductivity in the boson-fermion model

TL;DR

This paper investigates how non-magnetic disorder in either boson or fermion sites impacts s-wave superconductivity within the boson-fermion model, revealing that disorder generally suppresses superconductivity and affects different subsystems differently.

Contribution

It provides new insights into the effects of disorder on superconductivity in the boson-fermion model, highlighting subsystem-specific impacts.

Findings

Disorder in fermion sites mainly renormalizes the density of states.

Disorder in boson sites causes fluctuations in pairing strength.

Non-magnetic disorder is generally detrimental to s-wave superconductivity.

Abstract

We study how a randomness of either boson or fermion site energies affects the superconducting phase of the boson fermion model. We find that, contrary to what is expected for s-wave superconductors, the non-magnetic disorder is detrimental to the s-wave superconductivity. However, depending in which subsystem the disorder is located, we can observe different channels being affected. Weak disorder of the fermion subsystem is responsible mainly for renormalization of the single particle density of states while disorder in the boson subsystem directly leads to fluctuation of the strength of the effective pairing between fermions.