title: Evidence of electronic polarization of the As ion in the superconducting phase of F-doped LaFeAsO.
abstract: Understanding the nature of superconductivity in iron-based compounds is essential in the development of new strategies to increase T c. Using a charge density analysis based on synchrotron radiation X-ray powder diffraction data, we found that the charge carriers only accumulated in the iron layer of the superconducting phase of LaFeAsO1 - x F x at low temperatures. Analysis of the electrostatic potential distribution revealed the concerted enhancement of the electronic polarization of the As ions and the carrier redistribution. This suggests that the enhanced electronic polarization of the As ion plays an important role in inducing high T c superconductivity, and that the polaron concept, which has been previously regarded as an untenable mechanism, should be reconsidered for the description of the iron-arsenide superconducting phase.
authors: Japan Synchrotron Radiation Research Institute , Kouto, Sayo-cho, Hyogo 679-5198, Japan ; RIKEN SPring-8 Center , Kouto, Sayo-cho, Hyogo 679-5148, Japan.
authors: Jungeun
authors: J
authors: Kim
authors: Japan Synchrotron Radiation Research Institute , Kouto, Sayo-cho, Hyogo 679-5198, Japan.
authors: Akihiko
authors: A
authors: Fujiwara
authors: Department of Advanced Materials Science, The University of Tokyo , Kashiwa, Chiba 277-8561, Japan.
authors: Tomohiro
authors: T
authors: Sawada
authors: Department of Advanced Materials Science, The University of Tokyo , Kashiwa, Chiba 277-8561, Japan.
authors: Younghun
authors: Y
authors: Kim
authors: Japan Synchrotron Radiation Research Institute , Kouto, Sayo-cho, Hyogo 679-5198, Japan ; RIKEN SPring-8 Center , Kouto, Sayo-cho, Hyogo 679-5148, Japan.
authors: Kunihisa
authors: K
authors: Sugimoto
authors: Japan Synchrotron Radiation Research Institute , Kouto, Sayo-cho, Hyogo 679-5198, Japan ; RIKEN SPring-8 Center , Kouto, Sayo-cho, Hyogo 679-5148, Japan.
authors: Kenichi
authors: K
authors: Kato
authors: Department of Materials Science, Shimane University , 1060 Nishi-kawatsu-cho, Matsue, Shimane 690-8504, Japan.
authors: Hiroshi
authors: H
authors: Tanaka
authors: Comprehensive Research Organization for Science and Society (CROSS) , Ibaraki 319-1106, Japan ; Japan Atomic Energy Agency , Ibaraki 319-1195, Japan.
authors: Motoyuki
authors: M
authors: Ishikado
authors: Japan Atomic Energy Agency , Ibaraki 319-1195, Japan.
authors: Shin-Ichi
authors: S
authors: Shamoto
authors: Japan Synchrotron Radiation Research Institute , Kouto, Sayo-cho, Hyogo 679-5198, Japan ; RIKEN SPring-8 Center , Kouto, Sayo-cho, Hyogo 679-5148, Japan ; Department of Advanced Materials Science, The University of Tokyo , Kashiwa, Chiba 277-8561, Japan.
authors: Masaki
authors: M
authors: Takata
keywords: charge-carrier redistribution; electronic polarization; superconductivity