Microwave complex conductivity measurement of superconducting very thin FeSe1−xTex films (x = 0 - 0.5)

Abstract

Abstract In order to measure the complex conductivity of superconducting films much thinner than the penetration depth, for wide temperature range including the vicinity of T c, we developed a novel cavity pertubation technique utilizing microwave electric fields parallel to the film surface. By applying this newly developed technique to FeSe1−x Te x films, we found changes in the temperature dependence of the superfluid density and the quasiparticle scattering rate at the nematic boundary, which is in agreement with the results already obtained in the measurement in microwave magnetic field at lower temperatures. These changes in the nematic boundary suggests a variation in the superconducting gap structure between samples in the nematic and non-nematic phases.