title: Field-angle-dependent specific heat measurements and gap determination of a heavy fermion superconductor URu2Si2.
abstract: To identify the superconducting gap structure in URu2Si2, we perform field-angle-dependent specific heat measurements for the two principal orientations in addition to field rotations, and a theoretical analysis based on microscopic calculations. The Sommerfeld coefficient gamma(H)'s in the mixed state exhibit a distinctly different field dependence. This comes from point nodes and the substantial Pauli paramagnetic effect of URu2Si2. These two features combined give rise to a consistent picture of superconducting properties, including a possible first order transition of Hc2 at low temperatures.
authors.affiliation: Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 270-8581, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Yano
authors.forename: T
authors.initials: T
authors.lastname: Sakakibara
authors.forename: T
authors.initials: T
authors.lastname: Tayama
authors.forename: M
authors.initials: M
authors.lastname: Yokoyama
authors.forename: H
authors.initials: H
authors.lastname: Amitsuka
authors.forename: Y
authors.initials: Y
authors.lastname: Homma
authors.forename: P
authors.initials: P
authors.lastname: Miranović
authors.forename: M
authors.initials: M
authors.lastname: Ichioka
authors.forename: Y
authors.initials: Y
authors.lastname: Tsutsumi
authors.forename: K
authors.initials: K
authors.lastname: Machida