TEMPERATURE-DEPENDENCE OF THE SURFACE IMPEDANCE OF ND1.85CE0.15CUO4-YAND YBA2CU3O7-DELTA

We have measured the surface impedance of YBa2Cu3O7-delta (YBCO) singl e crystals, Nd1.85Ce0.15CuO4-y (NCCO) thin films and single crystals, and Nb single crystals at 9.6 GHz using a superconducting cavity pertu rbation technique. Our results on Nb ate in good agreement with s-wave BCS theory. The magnetic penetration depth in the ab-plane in YBCO si ngle crystals exhibits a linear temperature dependence at low temperat ures, and is consistent with clean 2D d-wave superconductivity. Both t hin films and single crystals of the electron-doped cuprate NCCO show detailed agreement with the predictions of single-gap isotropic s-wave BCS electrodynamics over the measured temperature range up to T-c.(1- 3)