Point-contact study of the LuNi2B2C borocarbide superconducting film

• Published in: Superconductor science & technology 2010-11, Vol.23 (11), p.115001-115001
• Main Authors: Kvitnitskaya, O E, Naidyuk, Yu G, Yanson, I K, Niemeier, T, Fuchs, G, Holzapfel, B, Schultz, L
• Format: Article
• Language: English
• Subjects: Borocarbides; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Joining; Nickel; Physics; Polycarbonates; Proximity effects, weak links, tunneling phenomena, and josephson effects, adreev effect, sn and sns junctions; Rare earth metals; Spectra; Superconducting films; Superconductivity
• ISSN: 0953-2048; 1361-6668
• DOI: 10.1088/0953-2048/23/11/115001

We present point-contact (PC) Andreev-reflection measurements of a superconducting epitaxial c-axis oriented nickel borocarbide film LuNi2B2C (Tc = 15.9 K). The averaged value of the superconducting gap is found to be meV in the one-gap approach, whereas the two-gap approach results in meV and meV. The better fit of the Andreev-reflection spectra for the LuNi2B2C--Cu PC obtained by the two-gap approach provides evidence for multiband superconductivity in LuNi2B2C. For the first time, PC electron--phonon interaction (EPI) spectra have been measured for this compound. They demonstrate a pronounced phonon maximum at 8.5 +/- 0.4 meV and a second shallow one at 15.8 +/- 0.6 meV. The electron--phonon coupling constant Delta *l estimated from the PC EPI spectra turned out to be small (with Delta *lPC ~ 0.1), like in other superconducting rare-earth nickel borocarbides. Possible reasons for this are discussed.