Orientational control of CeO2 buffer layers on A-plane sapphire substrates for REBa2Cu3O7−σ thin films

Abstract We attempted the epitaxial growth of CeO 2 on A-plane Al 2 O 3 ( 1 1 2 ¯ 0 ) (A-Al 2 O 3 ) substrates. As a buffer layers, CeO 2 layers (CeO 2 -I) were firstly prepared on A-Al 2 O 3 substrates at room temperature, and crystallized by ex situ annealing. The second CeO 2 layers (CeO 2 -II) were deposited on CeO 2 -I. The thickness of CeO 2 -I dependence of the characteristics of CeO 2 -II and EuBa 2 Cu 3 O 7− σ (EBCO) thin films, which were deposited on CeO 2 -II, was investigated. The CeO 2 -II layer completely was oriented along the c axis, while the in-plane orientation was not perfect. The critical current density ( J c ) decreased with degrading the in-plane orientation of EBCO thin films. It is found that the in-plane orientation of EBCO thin films greatly effected on J c . The best J c value at 77.3 K of EBCO thin films was 1.9 MA/cm 2 .