Electronic and crystal structures of Ln FeAsO 1- x H x ( Ln = La, Sm) studied by x-ray absorption spectroscopy, x-ray emission spectroscopy, and x-ray diffraction (part I: carrier-doping dependence).

Autor: Yamamoto Y; Graduate School of Science and Technology, Kwansei Gakuin University, Sanda, Hyogo 669-1337, Japan., Yamaoka H; RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan., Uozumi T; Department of Physics and electronics, Osaka Prefecture University, 1-1 Gakuen, Nakaku, Sakai, Osaka 599-8531, Japan., Hariki A; Department of Physics and electronics, Osaka Prefecture University, 1-1 Gakuen, Nakaku, Sakai, Osaka 599-8531, Japan., Onari S; Department of Physics, Nagoya University, Chikusa, Nagoya 464-8602, Japan., Yamaura JI; Materials Research Center for Element Strategy, Tokyo Institute of Technology, Yokohama, Kanagawa 226-8503, Japan., Ishii K; Synchrotron Radiation Research Center, National Institutes for Quantum and Radiological Science and Technology, Hyogo 679-5148, Japan., Kawai T; Graduate School of Science and Technology, Kwansei Gakuin University, Sanda, Hyogo 669-1337, Japan., Yoshida M; Graduate School of Science and Technology, Kwansei Gakuin University, Sanda, Hyogo 669-1337, Japan., Taguchi M; Toshiba Nanoanalysis Corporation, Kawasaki, Kanagawa 212-8583, Japan., Kobayashi K; Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801, Japan., Lin JF; Department of Geological Sciences, The University of Texas at Austin, Austin, Texas 78712, United States of America., Hiraoka N; National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan., Ishii H; National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan., Tsuei KD; National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan., Okanishi H; Laboratory for Materials and Structures, Tokyo Institute of Technology, Yokohama 226-8503, Japan., Iimura S; Laboratory for Materials and Structures, Tokyo Institute of Technology, Yokohama 226-8503, Japan., Matsuishi S; Laboratory for Materials and Structures, Tokyo Institute of Technology, Yokohama 226-8503, Japan., Hosono H; Materials Research Center for Element Strategy, Tokyo Institute of Technology, Yokohama, Kanagawa 226-8503, Japan.; Laboratory for Materials and Structures, Tokyo Institute of Technology, Yokohama 226-8503, Japan., Mizuki J; Graduate School of Science and Technology, Kwansei Gakuin University, Sanda, Hyogo 669-1337, Japan.
Jazyk: angličtina
Zdroj: Journal of physics. Condensed matter : an Institute of Physics journal [J Phys Condens Matter] 2021 May 28; Vol. 33 (25). Date of Electronic Publication: 2021 May 28.
DOI: 10.1088/1361-648X/abf9b9
Abstrakt: A carrier doping by a hydrogen substitution in LaFeAsO 1- x H x is known to cause two superconducting (SC) domes with the magnetic order at both end sides of the doping. In contrast, SmFeAsO 1- x H x has a similar phase diagram but shows single SC dome. Here, we investigated the electronic and crystal structures for iron oxynitride Ln FeAsO 1- x H x ( Ln = La, Sm) with the range of x = 0-0.5 by using x-ray absorption spectroscopy, x-ray emission spectroscopy, and x-ray diffraction. For both compounds, we observed that the pre-edge peaks of x-ray absorption spectra near the Fe- K edge were reduced in intensity on doping. The character arises from the weaker As-Fe hybridization with the longer As-Fe distance in the higher doped region. We can reproduce the spectra near the Fe- K edge according to the Anderson impurity model with realistic valence structures using the local-density approximation (LDA) plus dynamical mean-field theory (DMFT). For Ln = Sm, the integrated-absolute difference (IAD) analysis from x-ray Fe- Kβ emission spectra increases significantly. This is attributed to the enhancement of magnetic moment of Fe 3 d electrons stemming from the localized picture in the higher doped region. A theoretical simulation implementing the self-consistent vertex-correction method reveals that the single dome superconducting phase for Ln = Sm arises from a better nesting condition in comparison with Ln = La.
(© 2021 IOP Publishing Ltd.)
Databáze: MEDLINE
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