Microstructure of a-axis oriented YBCO films on SrTiO3 substrates using a new template layer La4BaCu5O13

Abstract a -axis oriented YBa 2 Cu 3 O 7− δ (YBCO) films on La 4− x Ba x Cu 5 O 13− δ (LBCO) template layers and multilayer structures with La 4− x Ba x Cu 5 O 13− δ as intermediate layer have been characterized by X-ray diffraction and high resolution electron microscopy. La 4− x Ba x Cu 5 O 13− δ as template layer induces a -axis growth of YBa 2 Cu 3 O 7− δ films with T c ( R = 0)= 81 K although the presence of c -axis domains at the interface is not entirely suppressed. Depending on the deposition temperature, this material can take the form of a disordered perovskite or exhibits a local ordering between the La and Ba cations of the type A 4 B. Moreover La 4− x Ba x Cu 5 O 13− δ can be used as a intermediate layer for SNS-type structures permitting the growth of a second YBCO layer in a -axis orientation.