title: Anisotropy of the superconducting gap of the borocarbide superconductor YNi2B2C with ultrasonic attenuation.
abstract: The ultrasonic attenuation alpha of the highly anisotropic s-wave superconductor YNi2B2C has been measured for all the symmetrically independent elastic modes to explore the location of the zero superconducting gap region on the Fermi surface. The attenuation of the longitudinal mode shows a pronounced anisotropy in the superconducting state: While alpha shows a thermally activated behavior along [110] and [001] directions, it shows T-linear dependence along [100]. These results together with those for the transverse modes demonstrate the presence of point nodes or zero-gap regions along [100] and [010] directions. This is a clear demonstration of ultrasonic attenuation as a powerful probe for the structure of the anisotropic superconducting gap.
authors.affiliation: Department of Advanced Materials Science and Applied Chemistry, University of Tokyo, Kashiwa, Chiba 277-8565, Japan.
authors.forename: Tadataka
authors.initials: T
authors.lastname: Watanabe
authors.forename: Minoru
authors.initials: M
authors.lastname: Nohara
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Hanaguri
authors.forename: Hidenori
authors.initials: H
authors.lastname: Takagi