title: Multiple superconducting phases in new heavy fermion superconductor PrOs4Sb12.
abstract: The superconducting gap structure of recently discovered heavy fermion superconductor PrOs4Sb12 was investigated by using thermal transport measurements in magnetic field rotated relative to the crystal axes. We demonstrate that a novel change in the symmetry of the superconducting gap function occurs deep inside the superconducting state, giving a clear indication of the presence of two distinct superconducting phases with twofold and fourfold symmetries. We infer that the gap functions in both phases have a point node singularity, in contrast to the familiar line node singularity observed in almost all unconventional superconductors.
authors.affiliation: Institute for Solid State Physics, University of Tokyo, Kashiwanoha 5-1-5, Kashiwa, Chiba 277-8581, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Izawa
authors.forename: Y
authors.initials: Y
authors.lastname: Nakajima
authors.forename: J
authors.initials: J
authors.lastname: Goryo
authors.forename: Y
authors.initials: Y
authors.lastname: Matsuda
authors.forename: S
authors.initials: S
authors.lastname: Osaki
authors.forename: H
authors.initials: H
authors.lastname: Sugawara
authors.forename: H
authors.initials: H
authors.lastname: Sato
authors.forename: P
authors.initials: P
authors.lastname: Thalmeier
authors.forename: K
authors.initials: K
authors.lastname: Maki