Date of Award
Doctor of Philosophy
Physics and Astronomy
Conventional Nb tunneling junction have been fabricated by completely oxidizing a 10-15 (ANGSTROM) layer of deposited Al avoiding thermal oxidation of the Nb. Comparison of the resulting conventional Nb pair potential and Eliashberg spectral function, (alpha)('2)F((omega)), with those of proximity (PETS) analyses shows excellent agreement confirming the appropriateness and accuracy of the PETS analytic procedure. The PET methodology is further adapted to proximity systems employing Mg as the N-layer backed by Nb and Ta foils S. A detailed study of C-MgO(,x)-MgNb systems for Mg thicknesses ranging from 25 (ANGSTROM) to 1100 (ANGSTROM) and C-MgO(,x)-MgTa systems over a narrower thickness range shows anomalous thickness dependence for the junction conductance resulting from an increased scattering presence over that seen in Al Nb systems. As a result the Nb phonon contributions are completely damped for Mg thicknesses greater than 400 (ANGSTROM), allowing unimpeded determination of the Mg (alpha)('2)F((omega)). The resulting Eliashberg spectral function reveals the electron-phonon coupling, (alpha)('2)((omega)), to be greatly reduced for transverse phonon frequencies relative to its longitudinal phonon value;In preface to the presentation of these studies, a detailed summary of the underlying theory and description of the experimental techniques and analytic methods are presented.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/
David Michael Burnell
Burnell, David Michael, "A proximity electron tunneling study of superconductivity in transition metals and as induced in a 'normal' metal, Mg " (1982). Retrospective Theses and Dissertations. 8334.