Localized Bosonic Modes in Superconductors

TL;DR

This paper demonstrates that localized bosonic modes create distinctive bound or resonance states in superconductors, affecting the density of states and providing signatures different from impurities.

Contribution

It introduces the concept of localized bosonic modes as a new type of defect in superconductors and analyzes their spectral signatures.

Findings

Localized bosonic modes induce characteristic peaks in the DOS.

The shape and energy of peaks depend on temperature and mode parameters.

Distinct signatures differentiate these modes from impurity effects.

Abstract

We show that a localized bosonic mode acts as a new type of "defect" in s- and d_{x^2-y^2}-wave superconductors. The mode induces bound or resonance states, whose spectral signature are peaks in the superconductor's density of states (DOS). We study the peaks' shape and energy as a function of temperature and the mode's frequency and lifetime. We identify several characteristic signatures of the localized mode that qualitatively distinguishes its effects from those of magnetic or non-magnetic impurities.