Mixed-state microwave response in superconducting cuprates

TL;DR

This study measures the microwave complex resistivity in superconducting cuprate thin films under magnetic fields, revealing that pair breaking, not vortex motion, explains the observed response.

Contribution

It demonstrates that field-induced pair breaking, rather than vortex dynamics, accounts for the microwave response in REBa2Cu3O7−δ superconductors.

Findings

Vortex motion models lead to inconsistent parameters.

Pair breaking explains the microwave response quantitatively.

Magnetic field effects are dominated by pair breaking mechanisms.

Abstract

We report measurements of the magnetic-field induced microwave complex resistivity in REBa$_{2}$Cu$_{3}$O$_{7-\delta}$ thin films, with RE = Y, Sm. Measurements are performed at 48 GHz by means of a resonant cavity in the end-wall-replacement configuration. The magnetic field dependence is investigated by applying a moderate (0.8 T) magnetic field along the c-axis. The measured vortex state complex resistivity in YBa$_{2}$Cu$_{3}$O$_{7-\delta}$ and SmBa$_{2}$Cu$_{3}$O$_{7-\delta}$ is analyzed within the well-known models for vortex dynamics. It is shown that attributing the observed response to vortex motion alone leads to inconsistencies in the as-determined vortex parameters (such as the vortex viscosity and the pinning constant). By contrast, attributing the entire response to field-induced pair breaking leads to a nearly quantitative description of the data.