Proximity electron-tunneling study of superconductivity in transition metals and as induced in a normal metal, Mg

Technical Report · Wed Jun 01 04:00:00 UTC 1983

OSTI ID:5994469

Burnell, D M

Conventional Nb tunneling junctions have been fabricated by completely oxidizing a 10 to 15 A layer of deposited Al, avoiding thermal oxidation of the Nb. Comparison of the resulting conventional Nb pair potential and Eliashberg spectral function, ..cap alpha../sup 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/sub x/-MgNb systems for Mg thicknesses ranging from 25 A to 1100 A and C-MgO/sub x/-MgTa systems over a narrower thickness range shows anamalous 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 A, allowing unimpeded determination of the Mg ..cap alpha../sup 2/F(..omega..). The resulting Eliashberg spectral function reveals the electron-phonon coupling, ..cap alpha../sup 2/(..omega..), to be greatly reduced for transverse phonon frequencies relative to its longitudinal phonon value.

• Research Organization: Ames Lab., IA (USA)
• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 5994469
• Report Number(s): IS-T-1073; ON: DE83016412
• Country of Publication: United States
• Language: English

Related Subjects

420201* -- Engineering-- Cryogenic Equipment & Devices
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ALKALINE EARTH METALS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELECTRON-PHONON COUPLING
ELEMENTS
JUNCTIONS
MAGNESIUM
METALS
NIOBIUM
PHONONS
PHYSICAL PROPERTIES
PROXIMITY EFFECT
QUASI PARTICLES
SUPERCONDUCTING JUNCTIONS
SUPERCONDUCTIVITY
TRANSITION ELEMENTS
TUNNEL EFFECT