A Coplanar Waveguide Resonator Technique for the Characterization of Iron-Based Superconductors

摘要

We present in detail a coplanar waveguide resonator (CPWR) method for the characterization of superconducting single crystals. It exploits the region of a CPWR where the rf magnetic field is quite homogeneous, by coupling a sample to it. Measurements are performed with and without the crystal, allowing a cavity perturbation approach. From the modifications in the resonance frequency and quality factor of the system it is possible to extract the London penetration depth and its anisotropy, quasiparticle conductivity, surface impedance and, when a coexisting magnetic phase is present, even bulk complex susceptibility.