The dc magnetic field, temperature and film thickness dependence of microwave surface resistance of YBCO and DyBCO thin films

Abstract

We investigated the dc magnetic field and temperature dependences of the microwave surface resistance (Rs) of YBa2Cu3Oy (YBCO) and DyBa2Cu3Oy (DyBCO) superconducting thin films. The YBCO and DyBCO thin films, each with a thickness of 300, 500, or 700nm, were deposited on MgO (100) substrates by the thermal co-evaporation method. The Rs was measured using the dielectric resonator method. A dc magnetic field of up to 5.0T was applied parallel to the c-axis of the superconducting thin films. The results showed that the Rs value had almost the same temperature dependence at various thicknesses in a zero-external field. The Rs of the YBCO and DyBCO thin films increased with the applied dc magnetic field. The DyBCO thin films showed weaker magnetic field dependence of Rs than the YBCO thin films. The Rs ratio (defined as Rs(5T)/Rs(0T)) linearly increased with the film thickness. These results show that pinning strength decreased with an increasing film thickness.