Reliable determination of vortex parameters from measurements of the microwave complex resistivity

TL;DR

This paper presents a model-independent method for accurately extracting vortex parameters like pinning constant and vortex viscosity from microwave resistivity measurements, accounting for thermal creep effects.

Contribution

It introduces a comprehensive data treatment approach that unifies various models into a single analytical expression, enabling precise vortex parameter estimation.

Findings

Able to estimate vortex parameters with bounds from single-frequency data

Thermal creep significantly affects vortex parameter determination

Neglecting thermal creep can lead to overestimating vortex viscosity

Abstract

We discuss and propose a complete data treatment, in close contact to typical microwave experimental data, in order to derive vortex parameters, such as pinning constant and viscous drag coefficient (also referred to as ``vortex viscosity''), in a way as model-independent as possible. We show that many of the accepted models for the complex resistivity can be described by a single, very general analytical expression. Using typical measurements of real and imaginary resistivity as a function of the applied field, we show that, even for single-frequency measurements, it is always possible to obtain (a) estimates of viscous drag coefficient and pinning constant with well-defined upper and lower bounds and (b) quantitative information about thermal creep. It turns out that neglecting thermal creep, in particular and counterintuitively at low temperatures, might result in a severe overestimation of the viscous drag coefficient. We also discuss the impact of thermal creep on the determination of the pinning constant. The present results might lead to a reconsideration of several estimates of the vortex parameters.