A comparative study of the surface resistances and microwave penetration depths of YBa2Cu3O7-delta thin films with various thicknesses

YBa2Cu3O7-delta (YBCO) thin films with different thicknesses were prepared and patterned into the forms of microstrip ring resonators with silver grounds, for which the microwave properties were studied at temperatures above the liquid nitrogen temperature and at frequencies of 8 to 12 GHz. The effective surface resistances of the YBCO thin films were calculated using Wheeler's incremental induction rule, from which the intrinsic surface resistances were calculated with a consideration of the finite-thickness effect on the surface resistance. The effective surface resistance of a YBCO film with larger thickness can be smaller than that of a YBCO film with a smaller thickness, depending on the ratio of the film thickness to the penetration depth.