Preparation of Bi-2212/YBCO heterostructure and their interfacial characters

YBa_(2)Cu_(3)O_(7‐x)(YBCO)thin films were prepared on LaAlO_(3)(LAO)substrates by a sol–gel method,and the epitaxial growth of Bi‐2212 thin films on YBCO thin films was investigated.Both YBCO and Bi_(2)Sr_(2)Ca1Cu_(2)O_(8)+δ(Bi‐2212)bilayer films exhibit good biaxial texture and superconducting properties.Afterward,a cross‐shaped Bi‐2212/YBCO heterostructure was fabricated,and its interfacial atomic arrangement and I‐V characteristics were analyzed.Atomic‐resolution STEM images obtained from a spherical‐aberration‐corrected transmission electron microscope show that two superconducting films exhibit a layered structure and the atoms inside the films are artfully arranged.Moreover,the order of the seven atomic layers between Bi‐2212 and YBCO layers with a thickness of about 1.32 nm is misarranged.Among them,the Y‐O layer of YBCO and the Sr‐O layer of Bi‐2212 share a CuO_(2) layer.The I‐V curves of Bi‐2212/YBCO bilayer films show that the seven misarranged atomic layers at Bi‐2212/YBCO interface acts as a barrier layer,which means that a Josephson junction can be fabricated using this interface characters.