Revisiting low-frequency susceptibility data in superconducting materials

TL;DR

This paper demonstrates that low-frequency susceptibility data in superconductors, when analyzed through a recent skin effect framework, can reveal the temperature dependence of superconducting electron concentration, emphasizing the importance of skin-depth measurements near T_c.

Contribution

It revisits old susceptibility data using a new analysis framework, showing how skin-depth measurements near T_c can provide insights into superconducting electron concentration.

Findings

Skin-depth measurements near T_c are crucial.

Old susceptibility data can be reinterpreted with the new framework.

The analysis clarifies the temperature dependence of superconducting electrons.

Abstract

Old susceptibility data, measured in superconducting materials at low-frequency, are shown to be accounted for consistently within the framework of a recently published\cite{sz1} analysis of the skin effect. Their main merit is to emphasize the significance of the skin-depth measurements, performed \textit{just beneath} the critical temperature $T_c$, in order to disprove an assumption, which thwarted any understanding of the skin-depth data, achieved so far by conventional high-frequency methods, so that those data might, from now on, give access to the temperature dependence of the concentration of superconducting electrons.