W.L. McLean

Superconducting coherence in bulk granular metals

Abstract Long-range phase coherence in bulk (three-dimensional) granular metals is governed by a variety of physical mechanisms. We discuss in particular the striking similarities to some behavior observed in discontinuous thin films that has been attributed to the topological ordering associated with the superconducting state in a two-dimensional system.

Superconductivity near the metal-insulator transition

Abstract Spin-orbit scattering is enhanced in granular aluminum by the addition of small amounts of bismuth. The metal-insulator transition is displaced to larger values of room-temperature resistivity. The superconducting-normal threshold is displaced by an approximately equal amount.

SUPERCONDUCTIVITY IN THIN FILMS OF Au/Si BY ION IMPLANTATION

Gold films on silicon substrates have been implanted with ions of Si, Ar, and Xe at tens of keV for the purpose of studying metastable phases inaccessible by other means of preparation. The recent prediction and discovery of superconductivity in the high- pressure hexagonal phases of silicon has called into question previous possible explanations of superconductivity in the Au/Si system.

Superconductivity in Pure La2CuO4

Detailed investigtions of the ground state properties of La2CuO4, have been made. Our data indicate traces of superconductivity in La2CuO4, with onset temperatues of 45K or higher. Results on three samples prepared from variable purity CuO (99.999%, 99.99%, 96%) indicate that superconductivity is an intrinsic property of La2CuO4 and not an artifact of impurity phase(s). Meisner signal as high as 0.3% has been observed. Indication for antiferromagnetic ordering near 210K is also apparent from both resitivity and magnetic susceptibility data.