Impedance determination of high-temperature superconductor film by combined microstrip resonator

Summary form only given. An original variant of high-temperature superconductor (HTS) film impedance determination using combined microstrip resonator (MSR) is presented. The significant advantage of the method is a possibility of HTS film properties investigation in applied external magnetic field. The method application for the HTS film properties investigation in an applied external magnetic field is illustrated. The aim of the paper is the presentation and approbation of the new variant of the HTS film impedance resonance determination method based on application of combined microstrip resonator (MSR). Significant disadvantage of common HTS MSR with strip and bottom plane made of HTS is the shielding effect that prevents carrying out complex physical experiments concerned with the action of an external magnetic field on HTS, for instance, the investigation of vortex dynamics, in such systems. This disadvantage can be neglected if combined MSR with strip made of HTS and bottom plate made of transparent to magnetic field material is used; magnetic field can penetrate the bottom pane and dielectric substrate and make influence on the HTS film. The experimental study of HTS film surface impedance was carried out for the thin YBa₂Cu₃O_7-δ films (YBCO) with thickness ~500 nm and the critical temperature of the transition origin T_C 90 K . The temperature dependency of YBCO strip surface resistance was obtained for the combined MSR. The estimation procedure for field dependence of surface resistance was the same as the procedure for temperature dependence. As result of this estimation, the field dependencies of the YBCO film surface resistance R_S(B) were obtained for different direction of magnetic field relative to the axis c.