Strain effect on microwave surface resistance of YBa2Cu3O7-δ/LaAlO3 and Tl2Ba2CaCu2O8/LaAlO3 high temperature superconducting thin films

Abstract

YBa2Cu3O7-δ (YBCO) thin films were prepared by thermal coevaporation on (LaAlO3) LAO substrates,and Tl2Ba2CaCu2O8 (TBCCO) thin films were synthesized by magnetron sputtering method on LAO substrates. We obtained the strain from the results of XRD of the films,which had the values of ΔCY=48483×10-3 and ΔCT=85272×10-5. We found that the strain in YBCO was larger than that in TBCCO. In addition, the curve of surface resistance of the films as a funttion of temperature was obtained by coplanar resonator technique, which showed the resistance of YBCO was larger than that of TBCCO at the same reduced temperature. In the paper, we also analyzed the strain effect on the surface resistance of the films.