title: Evidence for nodal quasiparticles in the nonmagnetic superconductor YNi2B2C via field-angle-dependent heat capacity.
abstract: Field-angle dependent heat capacity of the nonmagnetic borocarbide superconductor YNi2B2C reveals a clear fourfold oscillation, the first observation of its kind. The observed angular variations were analyzed as a function of magnetic field angle, field-intensity, and temperature to provide its origin. The quantitative agreement between experiment and theory strongly suggests that we are directly observing nodal quasiparticles generated along <100> by the Doppler effect. The results demonstrate that field-angle heat capacity can be a powerful tool in probing the momentum-space gap structure in unconventional superconductors such as high T(c) cuprates, heavy-fermion superconductors, etc.
authors.affiliation: Department of Physics and Material Research Laboratory, University of Illinois at Urbana-Champaign, Illinois 61801, USA.
authors.forename: Tuson
authors.initials: T
authors.lastname: Park
authors.forename: M B
authors.initials: MB
authors.lastname: Salamon
authors.forename: Eun Mi
authors.initials: EM
authors.lastname: Choi
authors.forename: Heon Jung
authors.initials: HJ
authors.lastname: Kim
authors.forename: Sung-Ik
authors.initials: SI
authors.lastname: Lee