Double Layer Processes of LBMO/YBCO and Crystalline Degradations

摘要

Double-layers of YBCO on LBMO and LBMO on YBCO were fabricated by ion beam sputtering technique. In the case of YBCO/LBMO, excellent a- and c-oriented overlying YBCO can be grown on underlying LBMO at 600- 650℃. Crystallinity of the overlying YBCO is nearly the same with that of YBCO single-layers on MgO and LaAlO_3 (LAO) substrates. Mosaicity of YBCO overlayer is much better than that of YBCO single-layers on MgO. It is noticed that the crystallinity of underlying LBMO can be improved, and the mosaicity is not degraded during the double-layer deposition. However, the inferiority is that surface roughness of the double-layer is much degraded. In the case of LBMO/YBCO, the excellent crystalline LBMO can be grown on the underlying a- and c-oriented YBCO at 650-700℃. LBMO/a-YBCO clearly shows XRD peak separation but LBMO/c-YBCO does not show the peak separation. Time dependences of the crystalline degradations on YBCO/LBMO double-layers and corresponding single-layers are presented as well. The crystallinity of YBCO/MgO is easily degraded with time, but that of YBCO/LAO does not show the degradation. LBMO is stable if it is covered with YBCO overlayer.