Electron and hole transmission through superconductor - Normal metal interfaces

: Gloos K, Tuuli E

: The Korean Physical Society

Publisher: KOREAN PHYSICAL SOC

: 2013

: Journal- Korean Physical Society

: Journal of the Korean Physical Society

: JOURNAL OF THE KOREAN PHYSICAL SOCIETY

: J KOREAN PHYS SOC

: 19th International Conference on Magnetism

: 10

: 62

: 10

: 1575

: 1579

: 5

: 0374-4884

DOI: https://doi.org/10.3938/jkps.62.1575

We have investigated the transmission of electrons and holes through interfaces between superconducting aluminum (T (c) = 1.2K) and various normal non-magnetic metals (copper, gold, palladium, platinum, and silver) using Andreev-reflection spectroscopy at T = 0.1K. We analysed the point contacts with the modified BTK theory that includes Dynes' lifetime as a fitting parameter I" in addition to superconducting energy gap 2 Delta and normal reflection described by Z. For contact areas from 1 nm(2) to 10000nm(2) the BTK Z parameter was 0.5, corresponding to transmission coefficients of about 80%, independent of the normal metal. The very small variation of Z indicates that the interfaces have a negligible dielectric tunneling barrier. Fermi surface mismatch does not account for the observed transmission coefficient.