Improved N-layer materials for high-T_c superconductor/normal-metal/superconductor junctions and superconducting quantum interference device sensors

In order to solve some of the formidable problems related to producing reliable and reproducible cuprate superconductor/normal-metal/superconductor (SNS) junctions, new N-layer compounds from the family of R_1-xCa_xBa_2-yLa_yCu_3-zM_zO_7-δ (R=Y, Gd and Pr; M=Co, Ni and Zn; 0≤x≤0.4; 0≤y≤0.4; 0≤z≤0.4) have been synthesized and their properties characterized. Thus, a crystal engineering approach has been adopted in an effort to generate reliable materials for use in high T_c superconducting devices. Careful analyses of the various prepared phases reveal optimum substitution levels for selected compositions where the N-layer compounds exhibit structures compatible with common superconductor electrode materials. The new compounds have been used for demonstration purposes as the N-layer material for the construction of ramp-edge-geometry SNS junctions and superconducting quantum interference device sensors. © 1998 American Institute of Physics.