Millimeter-wave complex-conductivity measurements of Bi-Ca-Sr-Cu-O superconducting thin films

Abstract

The first experimental determination of the complex conductivity ${\ensuremath{\sigma}}_{1}(T)$ and ${\ensuremath{\sigma}}_{2}(T)$ of superconducting oriented polycrystalline thin films of Bi-Ca-Sr-Cu-O has been made at 60 GHz. A sharp rise in ${\ensuremath{\sigma}}_{1}$ is observed below ${T}_{c}$. The microwave data can be fit by a model of superconducting grains nucleating in a normal conducting matrix. The penetration depth at 40 K deduced from this model is 1.3 \ensuremath{\mu}m.