title: Characteristic two-dimensional Fermi surface topology of high-Tc iron-based superconductors.
abstract: Unconventional Cooper pairing originating from spin or orbital fluctuations has been proposed for iron-based superconductors. Such pairing may be enhanced by quasi-nesting of two-dimensional electron and hole-like Fermi surfaces (FS), which is considered an important ingredient for superconductivity at high critical temperatures (high-Tc). However, the dimensionality of the FS varies for hole and electron-doped systems, so the precise importance of this feature for high-Tc materials remains unclear. Here we demonstrate a phase of electron-doped CaFe2As2 (La and P co-doped CaFe2As2) with Tc = 45 K, which is the highest Tc found for the AEFe2As2 bulk superconductors (122-type; AE = Alkaline Earth), possesses only cylindrical hole- and electron-like FSs. This result indicates that FS topology consisting only of two-dimensional sheets is characteristic of both hole- and electron-doped 122-type high-Tc superconductors.
authors.affiliation: 1] The Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan [2] Research Laboratory for Surface Science, Okayama University, 3-1-1 Tsushima-naka, Okayama 700-8530, Japan.
authors.forename: Masanori
authors.initials: M
authors.lastname: Sunagawa
authors.affiliation: 1] The Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan [2] Research Laboratory for Surface Science, Okayama University, 3-1-1 Tsushima-naka, Okayama 700-8530, Japan.
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Ishiga
authors.affiliation: 1] The Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan [2] Research Laboratory for Surface Science, Okayama University, 3-1-1 Tsushima-naka, Okayama 700-8530, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Tsubota
authors.affiliation: 1] The Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan [2] Research Laboratory for Surface Science, Okayama University, 3-1-1 Tsushima-naka, Okayama 700-8530, Japan.
authors.forename: Taihei
authors.initials: T
authors.lastname: Jabuchi
authors.affiliation: 1] The Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan [2] Research Laboratory for Surface Science, Okayama University, 3-1-1 Tsushima-naka, Okayama 700-8530, Japan.
authors.forename: Junki
authors.initials: J
authors.lastname: Sonoyama
authors.affiliation: 1] The Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan [2] Department of Physics, Okayama University, Okayama 700-8530, Japan.
authors.forename: Keita
authors.initials: K
authors.lastname: Iba
authors.affiliation: 1] The Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan [2] Department of Physics, Okayama University, Okayama 700-8530, Japan.
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Kudo
authors.affiliation: 1] The Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan [2] Department of Physics, Okayama University, Okayama 700-8530, Japan.
authors.forename: Minoru
authors.initials: M
authors.lastname: Nohara
authors.affiliation: Institute for Material Structure Science, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801.
authors.forename: Kanta
authors.initials: K
authors.lastname: Ono
authors.affiliation: Institute for Material Structure Science, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kumigashira
authors.affiliation: Japan Synchrotron Radiation Research Institute (JASRI)/SPring-8, 1-1-1 Kouto, Sayo, Hyogo 679-5198, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Matsushita
authors.affiliation: Hiroshima Synchrotron Radiation Center, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-0046, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Arita
authors.affiliation: Hiroshima Synchrotron Radiation Center, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-0046, Japan.
authors.forename: Kenya
authors.initials: K
authors.lastname: Shimada
authors.affiliation: Hiroshima Synchrotron Radiation Center, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-0046, Japan.
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Namatame
authors.affiliation: Hiroshima Synchrotron Radiation Center, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-0046, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Taniguchi
authors.affiliation: 1] The Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan [2] Research Laboratory for Surface Science, Okayama University, 3-1-1 Tsushima-naka, Okayama 700-8530, Japan.
authors.forename: Takanori
authors.initials: T
authors.lastname: Wakita
authors.affiliation: 1] The Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan [2] Research Laboratory for Surface Science, Okayama University, 3-1-1 Tsushima-naka, Okayama 700-8530, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Muraoka
authors.affiliation: 1] The Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan [2] Research Laboratory for Surface Science, Okayama University, 3-1-1 Tsushima-naka, Okayama 700-8530, Japan.
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Yokoya