Geometric resonance in intermediate state of type I superconductors

TL;DR

This paper investigates ultrasound attenuation in the intermediate state of type I superconductors, revealing oscillating behavior due to Andreev reflections, supported by theoretical modeling that explains experimental observations.

Contribution

It provides a theoretical explanation for the geometric resonance and ultrasound attenuation oscillations observed in type I superconductors' intermediate state.

Findings

Oscillating ultrasound attenuation dependent on magnetic field.

Amplitude modulation caused by Andreev reflections at boundaries.

Theoretical model aligns with experimental data.

Abstract

The attenuation of ultrasound (the geometric resonance) in an intermediate state of the type I superconductors at kaN >> 1 is researched. The oscillating dependence of ultrasound attenuation, which has an amplitude modulation as a result of presence of the Andreev reflec-tions by the electronic excitations on the boundaries between the normal metal layer and the superconducting layer in an intermediate state of the type I superconductor, is obtained. The derived theoretical equation explains the nature of experimental results in [1, 2].