Surface resistance of superconducting leads at 6.5 GHz

The quality factor (Q value) of a cylindrical TEO11 mode lead cavity has been measured at 6.5 GHz in the temperature range 1.4–4.2 K. Lead was electroplated on a copper substrate. The temperature dependence of the surface resistance derived from the Q measurements has been compared with the semi-empirical formula of Pippard and the microscopic formula of Abrikosov, Gorkov and Khalatnikov (AGK). The plot fit is better with AGK. In this way, the normalized residual resistance (5.0 ± 0.2) × 10^?4 and the energy gap Δ(0) = (4.30 ± 0.05)kT_c was obtained.