Microstructure and superconductivity of Bi-Sr-Ca-Cu-O/Bi-Sr-Cu-O multilayer thin films

Epitaxially grown multi-layers of Bi2Sr2CaCu2Oy (Bi-2212) and Bi2Sr2CuOx (Bi-2201) have been investigated referring to those microstructure and transport properties. Thin films have been prepared by a RF magnetron sputtering technique and laminated as the superconducting and non-superconducting layers. The samples have a variety of film thickness of each layer. The surface morphology, crystallization, diffusion and layered structures of these multi-layers were evaluated by TEM, AES, SIMS, STM-AFM and X-ray diffraction measurements. BSCO films exhibit normal conducting transport property even at 4.2 K. The superconducting properties such as a change of Tc, a broadening of the transition and anisotropy in those properties under magnetic field were discussed. Those results suggested that the structural and electronic condition in N-layer seriously affect the superconducting interlayer coupling between superconducting layers through non-superconducting layers