title: In-plane chemical pressure essential for superconductivity in BiCh2-based (Ch: S, Se) layered structure.
abstract: BiCh2-based compounds (Ch: S, Se) are a new series of layered superconductors, and the mechanisms for the emergence of superconductivity in these materials have not yet been elucidated. In this study, we investigate the relationship between crystal structure and superconducting properties of the BiCh2-based superconductor family, specifically, optimally doped Ce1-xNdxO0.5F0.5BiS2 and LaO0.5F0.5Bi(S1-ySey)2. We use powder synchrotron X-ray diffraction to determine the crystal structures. We show that the structure parameter essential for the emergence of bulk superconductivity in both systems is the in-plane chemical pressure, rather than Bi-Ch bond lengths or in-plane Ch-Bi-Ch bond angle. Furthermore, we show that the superconducting transition temperature for all REO0.5F0.5BiCh2 superconductors can be determined from the in-plane chemical pressure.
authors.affiliation: Department of Electrical and Electronic Engineering, Tokyo Metropolitan University, 1-1, Minami-osawa, Hachioji 192-0397, Japan.
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Mizuguchi
authors.affiliation: Faculty of Engineering, Hokkaido University, Kita-13, Nishi-8, Kita-ku, Sapporo 060-8628 Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Miura
authors.affiliation: Department of Electrical and Electronic Engineering, Tokyo Metropolitan University, 1-1, Minami-osawa, Hachioji 192-0397, Japan.
authors.forename: Joe
authors.initials: J
authors.lastname: Kajitani
authors.affiliation: Department of Electrical and Electronic Engineering, Tokyo Metropolitan University, 1-1, Minami-osawa, Hachioji 192-0397, Japan.
authors.forename: Takafumi
authors.initials: T
authors.lastname: Hiroi
authors.affiliation: Department of Electrical and Electronic Engineering, Tokyo Metropolitan University, 1-1, Minami-osawa, Hachioji 192-0397, Japan.
authors.forename: Osuke
authors.initials: O
authors.lastname: Miura
authors.affiliation: Faculty of Engineering, Hokkaido University, Kita-13, Nishi-8, Kita-ku, Sapporo 060-8628 Japan.
authors.forename: Kiyoharu
authors.initials: K
authors.lastname: Tadanaga
authors.affiliation: Center for Crystal Science and Technology, University of Yamanashi, 7-32 Miyamae, Kofu 400-8511 Japan.
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Kumada
authors.affiliation: Department of Physical Science, Hiroshima University, 1-3-1 Kagamiyama, Higashihiroshima, Hiroshima 739-8526 Japan.
authors.forename: Eisuke
authors.initials: E
authors.lastname: Magome
authors.affiliation: Department of Physical Science, Hiroshima University, 1-3-1 Kagamiyama, Higashihiroshima, Hiroshima 739-8526 Japan.
authors.forename: Chikako
authors.initials: C
authors.lastname: Moriyoshi
authors.affiliation: Department of Physical Science, Hiroshima University, 1-3-1 Kagamiyama, Higashihiroshima, Hiroshima 739-8526 Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Kuroiwa