Measurements of millimeter-wave surface resistance and temperature dependence of reactance of thin HTS films using quasi-optical dielectric resonator

The technique proposed by authors earlier for accurate measurement of large-area HTS thin film surface resistance (R_s) is developed further. It is based on application of quasioptical dielectric resonators (QDR). Data on R_s of individual Y-123 films obtained at 77 K by using "round robin" procedure are presented. The main attention is paid to developing technique of temperature dependence measurement of thin film surface reactance variation (ΔX_s). The dependence obtained by experiment is analyzed by means of fitting procedure that allows one to determine the validity of theoretical models for the temperature dependence of field penetration depth. Particularly, the 3D XY critical regime, Ginzburg-Landau behavior and two-fluid model are compared near T_c. Our data show that the former approach best follows the observed dependence.