title: Flux line lattice melting and the formation of a coherent quasiparticle Bloch state in the ultraclean URu2Si2 superconductor.
abstract: We find that in the ultraclean heavy-fermion superconductor URu(2)Si(2) (T_{c0}=1.45 K) a distinct flux line lattice melting transition with outstanding characters occurs well below the mean-field upper critical fields. We show that a very small number of carriers with heavy mass in this system results in exceptionally large thermal fluctuations even at sub-Kelvin temperatures, which are witnessed by a sizable region of the flux line liquid phase. The uniqueness is further highlighted by an enhancement of the quasiparticle mean free path below the melting transition, implying a possible formation of a quasiparticle Bloch state in the periodic flux line lattice.
authors.affiliation: Department of Physics, Kyoto University, Kyoto, Japan. okazaki@scphys.kyoto-u.ac.jp
authors.forename: R
authors.initials: R
authors.lastname: Okazaki
authors.forename: Y
authors.initials: Y
authors.lastname: Kasahara
authors.forename: H
authors.initials: H
authors.lastname: Shishido
authors.forename: M
authors.initials: M
authors.lastname: Konczykowski
authors.forename: K
authors.initials: K
authors.lastname: Behnia
authors.forename: Y
authors.initials: Y
authors.lastname: Haga
authors.forename: T D
authors.initials: TD
authors.lastname: Matsuda
authors.forename: Y
authors.initials: Y
authors.lastname: Onuki
authors.forename: T
authors.initials: T
authors.lastname: Shibauchi
authors.forename: Y
authors.initials: Y
authors.lastname: Matsuda