Microstructure and microwave surface resistance of YBCO films deposited under different oxygen pressures

Abstract YBa 2 Cu 3 O 7− x (YBCO) films with low microwave surface resistance ( R S ) are essential for high temperature superconducting microwave devices. The oxygen pressure during deposition has been found to influence R S significantly. In this work, we deposited highly c -axis aligned YBCO films on single crystal MgO (001) substrates under different oxygen pressures via pulsed laser ablation. Their detailed microstructure was characterized with three-dimensional reciprocal space mapping (3D-RSM) method and their microwave surface resistance was also measured with resonant cavity perturbation method. We found that the variation of oxygen pressure can affect film microstructure, including grain orientation distribution and the concentration of crystal defects. The microstructure modulation can explain R S dependence on the oxygen pressure.