Epitaxial growth of YBCO thin films on Al/sub 2/O/sub 3/ substrates by pulsed laser deposition

Superconducting YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) thin films were deposited on CeO/sub 2/ buffered Al/sub 2/O/sub 3/ (alumina and sapphire) substrates by pulsed laser deposition. Superconducting properties of the c-axis YBCO films on these substrates were greatly affected by the growth orientation of CeO/sub 2/ buffer layer. The critical temperature of YBCO film on alumina substrate was /spl sim/83 K. In the case of single crystal substrates, the critical temperature of YBCO thin film was /spl sim/89.5 K, and the critical current density was 1.5/spl times/10/sup 6/ A/cm/sup 2/ at 77 K.