Quasi-Particle Dynamics in Superconducting Aluminum

TL;DR

This study investigates how superconducting aluminum responds to electromagnetic radiation across a broad frequency and temperature range, focusing on quasi-particle dynamics, scattering, and coherence effects through complex conductivity measurements.

Contribution

It provides new insights into quasi-particle behavior and the effects of mean free path variations in superconducting aluminum.

Findings

Measured complex conductivity over broad frequency and temperature ranges.

Identified the relationship between mean free path and quasi-particle dynamics.

Enhanced understanding of scattering and coherence effects in superconductors.

Abstract

The response of superconducting aluminum to electromagnetic radiation is investigated in a broad frequency (45 MHz to 40 GHz) and temperature range ($T>T_c/2$), by measuring the complex conductivity. While the imaginary part probes the superfluid density (Cooper-pairs), the real part monitors the opening of the superconducting energy gap and -- most important here -- the zero-frequency quasi-particle response. Varying the mean free path gives some insight into the dynamics, scattering and coherence effects of the quasi-particles in the superconducting state.