Interaction of Ultrasound with Vortices in Type-II Superconductors

TL;DR

This paper presents a theoretical model of ultrasound interaction with vortices in type-II superconductors, highlighting the role of the Magnus force and predicting the conditions for observing the acoustic Faraday effect.

Contribution

It introduces a comprehensive theory incorporating Magnus force, anti-Magnus force, and diamagnetism to explain ultrasound behavior in the mixed state of superconductors.

Findings

The acoustic Faraday effect is linear in the Magnus force across flux flow regimes.

The effect is observable only in clean superconductors with large Magnus force.

Previous predictions of the effect's behavior are revised based on the new theory.

Abstract

The theory of the ultrasound propagation in the mixed state of type-II superconductors is suggested which takes into account the Magnus force on vortices, the anti-Magnus force on ions, and diamagnetism of the mixed state. The acoustic Faraday effect (rotation of polarization of the transverse ultrasonic wave propagating along vortices) is shown to be linear in the Magnus force in any regime of the flux flow for wavelengths used in the ultrasound experiments now. Therefore, in contrast to previous predictions, the Faraday effect should be looked for only in clean superconductors with a large amplitude of the Magnus force.