The effect of lattice matching between buffer layer and YBa2Cu3O7-δ thin film on in-plane alignment of C-axis oriented thin films

The effect of lattice matching between YBa2Cu3O7-delta (YBCO) films and buffer layers as well as between buffer layers and MgO substrates have been discussed from viewpoints of crystalline, critical temperature and surface resistance of YBCO films. SrSnO3 (SSO) as well as BaSnO3 (BSO) were used as buffer materials. SSO has closer lattice constant to YBCO than BSO. YBCO films were grown on these materials at the optimal growth temperature by pulse laser deposition. The FWHM of phi -scan (102) plane of YBCO films on SSO buffer lavers was smaller than that of YBCO films on BSO buffer layers. However the values of FWHM of 005 rocking-curve of YBCO films on BSO buffer layer were smaller than that of YBCO films on SSO buffer layer. The difference of surface resistance between YBCO film on BSO buffer layer and YBCO film on SSO buffer layer was very small indicating superconducting properties are not mainly governed by lattice mismatch at this region. We obtained the same values for c-axis length and critical temperature in YBCO films on these materials.