Temperature and dc magnetic field dependence of the surface resistance in HTS films

Abstract

We investigated the dependence of the surface resistance (Rs) in high-temperature superconductor (HTS) thin films on a dc magnetic field (parallel to the c-axis) and temperature. Measurements were done using the dielectric resonator method and superconducting magnet system. The YBa2Cu3O7−δ (YBCO) and DyBa2Cu3O7−δ (DyBCO) thin films produced by THEVA GmbH were prepared through a thermal co-evaporation method. The Rs of the YBCO and DyBCO thin films increased with magnitude of a dc magnetic field. The Rs(5T)/Rs(0T) of the DyBCO was lower than that of the YBCO thin films for the temperature region below 40K. From the results of the field-cooled (FC) and zero-field-cooled (ZFC) measurements of Rs, it was found that there was plenty of flux pinning in the DyBCO thin films compared with the YBCO thin films. These results indicate that the DyBCO thin films with much pinning centers are better for use in low temperature nuclear magnetic resonance applications.