title: Signature of highTcabove 25 K in high quality superconducting diamond.
abstract: We have observed zero resistivity above 10 K and an onset of resistivity reduction at 25.2 K in a heavily B-doped diamond film. However, the effective carrier concentration is similar to that of superconducting diamond with a lowerTc. We found that the carrier has a longer mean free path and lifetime than in the previous report, indicating that this highestTcdiamond has better crystallinity compared to that of other superconducting diamond films. In addition, the susceptibility shows a small transition above 20 K in the high quality diamond, suggesting a signature of superconductivity above 20 K. These results strongly suggest that heavier carrier doped defect-free crystalline diamond could give rise to highTcdiamond.
authors.affiliation: National Institute for Materials Science , 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Okazaki
authors.affiliation: The Graduate School of Natural Science and Technology, Okayama University , 3-1-1 Tsushima-naka, Okayama 700-8530, Japan.
authors.forename: Takanori
authors.initials: T
authors.lastname: Wakita
authors.affiliation: Japan Synchrotron Radiation Research Institute (JASRI)/SPring-8 , 1-1-1 Kouto, Sayo, Hyogo 679-5198, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Muro
authors.affiliation: Japan Synchrotron Radiation Research Institute (JASRI)/SPring-8 , 1-1-1 Kouto, Sayo, Hyogo 679-5198, Japan.
authors.forename: Tetsuya
authors.identifier: 0000-0001-5647-9477
authors.initials: T
authors.lastname: Nakamura
authors.affiliation: The Graduate School of Natural Science and Technology, Okayama University , 3-1-1 Tsushima-naka, Okayama 700-8530, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Muraoka
authors.affiliation: The Graduate School of Natural Science and Technology, Okayama University , 3-1-1 Tsushima-naka, Okayama 700-8530, Japan.
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Yokoya
authors.affiliation: School of Science and Engineering, Waseda University , 3-4-1 Okubo, Shinjuku, Tokyo 169-8555, Japan.
authors.forename: Shin-Ichiro
authors.initials: SI
authors.lastname: Kurihara
authors.affiliation: School of Science and Engineering, Waseda University , 3-4-1 Okubo, Shinjuku, Tokyo 169-8555, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kawarada
authors.affiliation: Institute of Scientific and Industrial Research, Osaka University , 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan.
authors.forename: Tamio
authors.identifier: 0000-0001-7109-2801
authors.initials: T
authors.lastname: Oguchi
authors.affiliation: National Institute for Materials Science , 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan.
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Takano