A method based on a dual frequency resonator to estimate physical parameters of superconductors from surface impedance measurements in a magnetic field

TL;DR

This paper introduces a dual frequency resonator method to accurately estimate the crossover frequency and surface resistance of superconductors in magnetic fields, improving upon traditional single-frequency techniques.

Contribution

It presents a novel combined analytical and experimental approach using dual frequency resonators to better estimate superconductor parameters and validate physical models.

Findings

Single-frequency methods underestimate surface resistance.

Dual frequency approach yields more accurate  estimates.

Method enables testing of physical models.

Abstract

High frequency applications of superconductors in a dc magnetic field rely on the estimate of the characteristic crossover frequency $\nu_c$ between low and high losses. Customarily, high sensitivity resonant techniques, intrinsically operating at discrete frequencies, are used to estimate $\nu_c$. We exploit here a method based on a dual frequency resonator. We show that single-frequency evaluations of $\nu_c$ lead to heavy underestimations of the superconductor surface resistance. We describe a combined analytical and experimental approach that gives more accurate estimates for $\nu_c$, and additionally allows to test the underlying physical model.