Ultrasonic attenuation in a pseudogapped superconductor

TL;DR

This paper presents a theoretical model for ultrasonic attenuation in pseudogapped superconductors, proposing a new method to measure the superconducting collective gap using ultrasound decay rates at low temperatures.

Contribution

It introduces a theory linking ultrasound decay rate to the collective gap in pseudogapped superconductors, enabling gap measurement in the presence of a strong pseudogap.

Findings

Decay rate $oldsymbol{eta}$ is controlled by the ratio $oldsymbol{T/oldsymbol{ riangle}}$ at low temperatures.

Ultrasound attenuation provides a new experimental method to measure the collective gap $oldsymbol{ riangle}$.

The theory applies to superconductors with a large pseudogap $oldsymbol{ riangle_P}$.

Abstract

We develop a theory of ultrasound decay rate $\alpha$ in a model of a superconductor with a large pseudogap $\Delta_P$, and show that at low temperatures ($T \ll T_c$) the magnitude of the decay rate $\alpha$ is controlled by the ratio of $T/\Delta$, where $\Delta \ll \Delta_P$ is a superconducting collective gap. Thus we propose new method to measure the collective gap $\Delta$ in a situation when strong pseudogap is present.