Electron renormalization of sound interaction with two-level systems in superconducting metglasses

TL;DR

This paper investigates how the superconducting transition affects sound interaction with two-level systems in metallic glasses, highlighting electron coupling effects on sound velocity and attenuation.

Contribution

It introduces a simple model to qualitatively describe and quantitatively estimate the influence of superconductivity on sound interaction with TLS in metallic glasses.

Findings

Superconducting transition causes renormalization of sound interaction with TLS.

The model explains the temperature dependence of sound velocity in superconducting metallic glasses.

Quantitative estimations of renormalization parameters are provided.

Abstract

The crossing of temperature dependences of the sound velocity in normal and superconducting state of metallic glasses points out unambiguously the renormalization of the intensity of sound interaction with two-level systems (TLS), caused by their coupling with electrons. We propose a simple scenario which allows us to describe qualitatively the influence of the superconducting transition on the sound velocity and attenuation in superconducting metglasses and to make quantative estimations of renormalization parameters.