title: Observation of a superconducting gap in boron-doped diamond by laser-excited photoemission spectroscopy.
abstract: We investigate the temperature (T)-dependent low-energy electronic structure of a boron-doped diamond thin film using ultrahigh resolution laser-excited photoemission spectroscopy. We observe a clear shift of the leading edge below T=11 K, indicative of a superconducting gap opening (Delta approximately 0.78 meV at T=4.5 K). The gap feature is significantly broad and a well-defined quasiparticle peak is lacking even at the lowest temperature of measurement (=4.5 K). We discuss our results in terms of disorder effects on the normal state transport and superconductivity in this system.
authors.affiliation: Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Ishizaka
authors.forename: R
authors.initials: R
authors.lastname: Eguchi
authors.forename: S
authors.initials: S
authors.lastname: Tsuda
authors.forename: T
authors.initials: T
authors.lastname: Yokoya
authors.forename: A
authors.initials: A
authors.lastname: Chainani
authors.forename: T
authors.initials: T
authors.lastname: Kiss
authors.forename: T
authors.initials: T
authors.lastname: Shimojima
authors.forename: T
authors.initials: T
authors.lastname: Togashi
authors.forename: S
authors.initials: S
authors.lastname: Watanabe
authors.forename: C-T
authors.initials: CT
authors.lastname: Chen
authors.forename: C Q
authors.initials: CQ
authors.lastname: Zhang
authors.forename: Y
authors.initials: Y
authors.lastname: Takano
authors.forename: M
authors.initials: M
authors.lastname: Nagao
authors.forename: I
authors.initials: I
authors.lastname: Sakaguchi
authors.forename: T
authors.initials: T
authors.lastname: Takenouchi
authors.forename: H
authors.initials: H
authors.lastname: Kawarada
authors.forename: S
authors.initials: S
authors.lastname: Shin