Time-domain measurement of the surface resistance of YBa/sub 2/Cu/sub 3/O/sub 7/ superconducting films up to 500 GHz

The surface resistance and surface reactance of high-quality YBa/sub 2/Cu/sub 3/O/sub 7/ superconducting films were determined from 10 GHz to 500 GHz using time-domain propagation measurements of picosecond electrical pulses on coplanar transmission lines. For the surface resistance, the authors find a square law dependence with frequency almost up to 500 GHz and a crossover of the losses of gold and YBa/sub 2/Cu/sub 3/O/sub 7/ films at 77 K at roughly 100 GHz. The pulse propagation is successfully modeled using the Mattis-Bardeen theory for the frequency-dependent conductivity of YBa/sub 2/Cu/sub 3/O/sub 7/. Good quantitative agreement of the surface resistance and surface reactance with this theory is obtained. The potential of YBa/sub 2/Cu/sub 3/O/sub 7/ superconducting films and equivalent gold and superconducting films for high-speed applications is studied theoretically.