2013S2-002
元素戦略プロジェクト・電子材料領域における放射光利用研究：軽元素アニオン系における機能発現機構の解明

Last modified 2020-09-15 by s-proposalpfiqst.kek.jp

→関連サイト；元素戦略プロジェクト電子材料領域（東工大拠点）

●基本情報
　●実験責任者：村上　洋一（PF）
　●課題有効期間：2013/4〜2016/3
　●実験ステーション：2A/B, 3A, 4C, 8A/B, 16A, 28A/B, NE5C, NW10A, NW2A

●課題の概要
　今年度より国家プロジェクトとして「元素戦略プロジェクト」がスタートした。元素戦略プロジェクトでは、日本の産業競争力に直結する以下の４つの材料領域が選定された：電子材料領域、磁性材料領域、触媒・電池材料領域、構造材料領域。これらの材料領域では希少元素を用いない全く新しい材料開発を目指している。本研究申請は、その中の電子材料領域において「放射光・中性子・ミュオンを用いた材料評価・解析」を担うためのものである。KEKは副拠点となり、東工大拠点を中心とした材料創製グループが合成した材料を研究対象として、その材料の局所構造や系の電子構造・磁気構造を、中性子・放射光を用いて精密に決定する。
　本研究では、革新的電子材料の元素フロンティア開拓を目指し、放射光ならではの手段を用いて、材料機能発現機構の原子、電子レベルでの理解を通し、材料系のスクリーニング、材料設計のための指針を導き出すことを大きな目標としている。具体的な研究サブテーマとして、下記の４つを挙げる。
1. 固体エレクトライドにおける特異な電子状態の解明
2. 透明電極材料の電子状態の解明と材料スクリーニング
3. 軽元素ドープ鉄系超伝導体の構造と物性
4. アンモニア合成における新触媒の機能発現機構の解明
これらの系の研究において共通する考え方は、電子を含む軽元素アニオン系における機能発現機構の解明である、ということが言える。第１番目の研究テーマは、電子が0次元（C12A7系）、1次元（Ba₃N系）、2次元（R₂N(R = Ca, Sr, Ba)系）的な空間に閉じ込められた特異な系（エレクトライド）の電子状態を解明しようとするものである。第２番目の研究テーマにおいてもC12A7エレクトライドが重要な役割を担うことが期待されている。第3番目の研究テーマでは、有名な鉄系超伝導体においてO^2-の代わりにH^-アニオンが入ることにより、大きく超伝導領域が拡がるとともにその新しい超伝導メカニズムに注目が集まっている。第4番目の研究テーマは、Ru担持のC12A7エレクトライドによるアンモニア合成機構の研究である。

●成果発表
　●論文

• "Air-Stable Calcium Cyanamide-Supported Ruthenium Catalyst for Ammonia Synthesis and Decomposition"
  Kazuhisa Kishida, Masaaki Kitano, Masato Sasase, Peter V. Sushko, Hitoshi Abe, Yasuhiro Niwa, Kiya Ogasawara, Toshiharu Yokoyama, and Hideo Hosono
  ACS Appl. Enrgy Mater., 3 (2020) 6573.
• "Orbital Transitions and Frustrated Magnetism in the Kagome-Type Copper Mineral Volborthite"
  Zenji Hiroi, Hajime Ishikawa, Hiroyuki Yoshida, Jun-ichi Yamaura and Yoshihiko Okamoto
  Inorg. Chem., 58 (2019) 11949.
• "Crystal structure and magnetic properties of the 5d transition metal oxides AOsO₄(A = K, Rb, Cs)"
  Jun-ichi Yamaura and Zenji Hiroi
  Phys. Rev. B, 99 (2019) 155113.
• "Direct Activation of Cobalt Catalyst by 12CaO·7Al₂O₃ Electride for Ammonia Synthesis"
  Yasunori Inoue, Masaaki Kitano, Mai Tokunari, Teppei Taniguchi, Kayato Ooya, Hitoshi Abe, Yasuhiro Niwa, Masato Sasase, Michikazu Hara, and Hideo Hosono
  ACS Catal., 9 (2019) 1670.
• "Growth of antiperovskite oxide Ca₃SnO films by pulsed laser deposition"
  Makoto Minohara, Ryu Yukawa, Miho Kitamura, Reiji Kumai, Youichi Murakami, Hiroshi Kumigashira
  J. Cryst. Growth, 500 (2018) 33.
• "Spatial coherence of the insulating phase in quasi-two-dimensional LaNiO₃ films"
  Masato Anada, Kazuhiro Kowa, Hiroki Maeda, Enju Sakai, Miho Kitamura, Hiroshi Kumigashira, Osami Sakata, Yoshinori Nakanishi-Ohno, Masato Okada, Tsuyoshi Kimura, and Yusuke Wakabayashi
  Phys. Rev. B, 98 (2018) 014105.
• "Large Oblate Hemispheroidal Ruthenium Particles Supported on Calcium Amide as Efficient Catalysts for Ammonia Decomposition"
  Kazuhisa Kishida, Masaaki Kitano, Yasunori Inoue, Masato Sasase, Takuya Nakao, Tomofumi Tada, Hitoshi Abe, Yasuhiro Niwa, Toshiharu Yokoyama, Michikazu Hara, Hideo Hosono
  Chemistry, 24 (2018), 7976.
• "High Electron Density on Ru in Intermetallic YRu₂: The Application to Catalyst for Ammonia Synthesis"
  Takaya Ogawa, Yasukazu Kobayashi, Hiroshi Mizoguchi, Masaaki Kitano, Hitoshi Abe, Tomofumi Tada, Yoshitake Toda, Yasuhiro Niwa, and Hideo Hosono
  J. Phys. Chem. C, 122 (2018), 10468.
• "Amorphous Gallium Oxide as an Improved Host for Inorganic Light-Emitting Thin Film Semiconductor Fabricated at Room Temperature on Glass"
  Naoto Watanabe, Junghwan Kim, Keisuke Ide, Hidenori Hiramatsu, Hiroshi Kumigashira, Shigenori Ueda, Hideo Hosono and Toshio Kamiya
  ECS J. Solid State Sci. Technol., 6 (2017) P410.
• "Oxidation Number Estimation of Ca in Ca-N Compounds from Ca K-edge XANES Spectra"
  Hitoshi Abe, Yasuhiro Niwa, Masaaki Kitano, Yasunori Inoue, Toshiharu Yokoyama, Michikazu Hara, and Hideo Hosono
  Bull. Chem. Soc. Jpn., 90 (2017), 963.
• "Anchoring Bond between Ru and N Atoms of Ru/Ca₂NH Catalyst: Crucial for the High Ammonia Synthesis Activity"
  Hitoshi Abe, Yasuhiro Niwa, Masaaki Kitano, Yasunori Inoue, Masato Sasase, Takuya Nakao, Tomofumi Tada, Toshiharu Yokoyama, Michikazu Hara, and Hideo Hosono
  J. Phys. Chem. C, 121 (2017), 20900.
• "Semimetallic bands derived from interlayer electrons in the quasi-two-dimensional electride Y₂C"
  Koji Horiba, Ryu Yukawa, Taichi Mitsuhashi, Miho Kitamura, Takeshi Inoshita, Noriaki Hamada, Shigeki Otani, Naoki Ohashi, Sachiko Maki, Jun-ichi Yamaura, Hideo Hosono, Youichi Murakami, and Hiroshi Kumigashira
  Phys. Rev. B, 96 (2017) 045101.
• "Structure determination in thin film Ba_1−xLa_xFe₂As₂: Relation between the FeAs₄ geometry and superconductivity"
  Kensuke Kobayashi, Akiko Nakao, Sachiko Maki, Jun-ichi Yamaura, Takayoshi Katase, Hikaru Sato, Hajime Sagayama, Reiji Kumai, Yoshio Kuramoto, Youichi Murakami, Hidenori Hiramatsu, and Hideo Hosono
  Phys. Rev. B, 96 (2017) 125116.
• "Surface Electronic Structure of Proton-doped YSZ Thin Film by Soft-X-ray Photoemission Spectroscopy"
  Makoto Takayanagi, Takashi Tsuchiya, Makoto Minohara, Masaki Kobayashi, Koji Horiba, Hiroshi Kumigashira, Tohru Higuchi
  Trans. Mat. Res. Soc. Jpn., 42 (2017) 61.
• "Structural and Electrical Properties of BaPrO_3-δ Thin Film with Oxygen Vacancies"
  Shoto Furuichi, Takashi Tsuchiya, Koji Horiba, Masaki Kobayashi, Makoto Minohara, Hiroshi Kumigashira, Tohru Higuchi
  Trans. Mat. Res. Soc. Jpn., 42 (2017) 15.
• "Resonant photoemission and X-ray absorption spectroscopies of lithiated magnetite thin film"
  Takashi Tsuchiya, Kinya Kawamura, Wataru Namiki, Shoto Furuichi, Makoto Takayanagi, Makoto Minohara, Masaki Kobayashi, Koji Horiba, Hiroshi Kumigashira, Kazuya Terabe and Tohru Higuchi
  Jpn. J. Appl. Phys., 56 (2017) 04CK01.
• "Proton Conduction on YSZ Electrolyte Thin Films Prepared by RF Magnetron Sputtering"
  Makoto Takayanagi, Shoto Furuichi, Wataru Namiki, Takashi Tsuchiya, Makoto Minohara, Masaki Kobayashi, Koji Horiba, Hiroshi Kumigashira, and Tohru Higuchi
  ECS Trans., 75 (2017) 115.
• "Ion Conduction of BaPrO_3-δ Thin Film with Mixed Valence State for SOFC Anode Electrode"
  Shoto Furuichi, Takashi Tsuchiya, Makoto Minohara, Masaki Kobayashi, Koji Horiba, Hiroshi Kumigashira, and Tohru Higuchi
  ECS Trans., 75 (2017) 99.
• "Electron-Ion Mixed Conduction of Nd_0.6Sr_0.4FeO₃ Cathode Electrode Thin Film for Solid Oxide Fuel Cell"
  Wataru Namiki, Makoto Takayanagi, Shoto Furuichi, Takashi Tsuchiya, Makoto Minohara, Masaki Kobayashi, Koji Horiba, Hiroshi Kumigashira, and Tohru Higuchi
  ECS Trans., 75 (2017) 83.
• "Interlayer states arising from anionic electrons in the honeycomb-lattice-based compounds AeAlSi (Ae=Ca, Sr, Ba)"
  Yangfan Lu, Tomofumi Tada, Yoshitake Toda, Shigenori Ueda, Jiazhen Wu, Jiang Li, Koji Horiba, Hiroshi Kumigashira, Yaoqing Zhang, and Hideo Hosono
  Phys. Rev. B, 95 (2017) 125117.
• "Electron–Ion Mixed Conduction of BaCe_0.90Y_0.10O_3−δ Thin Film Generated by Ru Substitution"
  Masanori Ochi, Takashi Tsuchiya, Shohei Yamaguchi, Takaaki Suetsugu, Naoya Suzuki, Masaki Kobayashi, Makoto Minohara, Koji Horiba, Hiroshi Kumigashira, and Tohru Higuchi
  J. Phys. Soc. Jpn., 85 (2016) 034705.
• "Metal–insulator transition of valence-controlled VO₂ thin film prepared by RF magnetron sputtering using oxygen radical"
  Takaaki Suetsugu, Yuichi Shimazu, Takashi Tsuchiya, Masaki Kobayashi, Makoto Minohara, Enju Sakai, Koji Horiba, Hiroshi Kumigashira and Tohru Higuchi
  Jpn. J. Appl. Phys., 55 (2016) 06GJ11.
• "Electrical and structural properties of TiO_2−δ thin film with oxygen vacancies prepared by RF magnetron sputtering using oxygen radical"
  Kinya Kawamura, Naoya Suzuki, Takashi Tsuchiya, Yuichi Shimazu, Makoto Minohara, Masaki Kobayashi, Koji Horiba, Hiroshi Kumigashira and Tohru Higuchi
  Jpn. J. Appl. Phys., 55 (2016) 06GJ08.
• "Electronic structure of c-axis controlled α-Fe₂O₃ thin film probed by soft-X-ray spectroscopy"
  Kinya Kawamura, Naoya Suzuki, Takashi Tsuchiya, Shohei Yamaguchi, Masanori Ochi, Takaaki Suetsugu, Makoto Minohara, Masaki Kobayashi, Koji Horiba, Hiroshi Kumigashira and Tohru Higuchi
  Jpn. J. Appl. Phys., 55 (2016) 06GJ04.
• "Electrical and structural properties of BaCe_0.85Ru_0.05Y_0.10O_3−δ thin film prepared by RF magnetron sputtering"
  Masanori Ochi, Takashi Tsuchiya, Shohei Yamaguchi, Takaaki Suetsugu, Naoya Suzuki, Masaki Kobayashi, Makoto Minohara, Koji Horiba, Hiroshi Kumigashira and Tohru Higuchi
  Jpn. J. Appl. Phys., 55 (2016) 06GJ02.
• "High Oxidation Tolerance of Ru Nanoparticles on 12CaO·7Al₂O₃ Electride"
  Hitoshi Abe, Yasuhiro Niwa, Masaaki Kitano, Yasunori Inoue, Youichi Murakami, Toshiharu Yokoyama, Michikazu Hara, and Hideo Hosono
  J. Phys. Chem. C, 120 (2016) 8711.
• "Phonon-dressed two-dimensional carriers on the ZnO surface"
  R. Yukawa, K. Ozawa, S. Yamamoto, H. Iwasawa, K. Shimada, E. F. Schwier, K. Yoshimatsu, H. Kumigashira, H. Namatame, M. Taniguchi, and I. Matsuda
  Phys. Rev. B, 94 (2016) 165313.
• "Pressure effect on iron-based superconductor LaFeAsO_1−xH_x: Peculiar response of 1111-type structure"
  Kensuke Kobayashi, Jun-ichi Yamaura, Soshi Iimura, Sachiko Maki, Hajime Sagayama, Reiji Kumai, Youichi Murakami, Hiroki Takahashi, Satoru Matsuishi and Hideo Hosono
  Sci. Rep., 6 (2016) 39646.
• "Efficient and Stable Ammonia Synthesis by Self-Organized Flat Ru Nanoparticles on Calcium Amide"
  Yasunori Inoue, Masaaki Kitano, Kazuhisa Kishida, Hitoshi Abe, Yasuhiro Niwa, Masato Sasase, Yusuke Fujita, Hiroki Ishikawa, Toshiharu Yokoyama, Michikazu Hara, and Hideo Hosono
  ACS Catal., 6 (2016) 7577.
• "Influence of k_⊥ broadening on ARPES spectra of the (110) and (001) surfaces of SrVO₃ films"
  T. Mitsuhashi, M. Minohara, R. Yukawa, M. Kitamura, K. Horiba, M. Kobayashi, and H. Kumigashira
  Phys. Rev. B, 94 (2016) 125148.
• "Epitaxial synthesis and physical properties of double-perovskite oxide Sr₂CoRuO₆ thin films"
  K. Watarai, K. Yoshimatsu, K. Horiba, H. Kumigashira, O. Sakata and A. Ohtomo
  J. Phys.: Condens. Matter., 28 (2016) 436005.
• "Thickness-dependent physical properties of La_1/3Sr_2/3FeO₃ thin films grown on SrTiO₃ (001) and (111) substrates"
  Makoto Minohara, Miho Kitamura, Hiroki Wadati, Hironori Nakao, Reiji Kumai, Youichi Murakami and Hiroshi Kumigashira
  J. Appl. Phys., 120 (2016) 025303.
• "Gritty Surface Sample Holder Invented To Obtain Correct X-ray Absorption Fine Structure Spectra for Concentrated Materials by Fluorescence Yield"
  Hitoshi Abe, Yasuhiro Niwa, Masao Kimura, Youichi Murakami, Toshiharu Yokoyama, and Hideo Hosono
  Anal. Chem., 88 (2016) 3455.
• "Spatial distribution of transferred charges across the heterointerface between perovskite transition metal oxides LaNiO₃ and LaMnO₃"
  Miho Kitamura, Koji Horiba, Masaki Kobayashi, Enju Sakai, Makoto Minohara, Taichi Mitsuhashi, Atsushi Fujimori, Takuro Nagai, Hiroshi Fujioka and Hiroshi Kumigashira
  Appl. Phys. Lett., 108 (2016) 111603.
• "Isotropic Kink and Quasiparticle Excitations in the Three-Dimensional Perovskite Manganite La_0.6Sr_0.4MnO₃"
  Koji Horiba, Miho Kitamura, Kohei Yoshimatsu, Makoto Minohara, Enju Sakai, Masaki Kobayashi, Atsushi Fujimori, and Hiroshi Kumigashira
  Phys. Rev. Lett., 116 (2016) 076401.
• "Strong charge density wave fluctuation and sliding state in PdTeI with quasi-one-dimensional PdTe chains"
  Hechang Lei, Kai Liu, Jun-ichi Yamaura, Sachiko Maki, Youichi Murakami, Zhong-Yi Lu, and Hideo Hosono
  Phys. Rev. B, 93 (2016) 121101(R).
• "Hole-ion Mixed Conduction of Orientation-Controlled BaPrO_3-δ Thin Film with Mixed Valence States"
  Tohru Higuchi, Asuka Oda, Takashi Tsuchiya, Takaaki Suetsugu, Naoya Suzuki, Shohei Yamaguchi, Makoto Minohara, Masaki Kobayashi, Koji Horiba, and Hiroshi Kumigashira
  J. Phys. Soc. Jpn., 84 (2015) 114708.
• "Electron-Ion Mixed Conduction of Ru-Doped BaCe_0.9Y_0.1O_3-δ Thin Film"
  Tohru Higuchi, Tomoyuki Yamashita, Tomohiro Owaku, Yuichi Shimazu, Hiroyuki Kato, Masaki Kobayashi, Hiroshi Kumigashira
  Transactions of the Materials Research Society of Japan, 40 (2015) 429.
• "Electron Donation Enhanced CO Oxidation over Ru-Loaded 12CaO⋅7Al₂O₃ Electride Catalyst"
  Md Jafar Sharif, Masaaki Kitano, Yasunori Inoue, Yasuhiro Niwa, Hitoshi Abe, Toshiharu Yokoyama, Michikazu Hara, and Hideo Hosono
  J. Phys. Chem. C, 119 (2015) 11725.
• "Fermi surfaces and p−d hybridization in the diluted magnetic semiconductor Ba_1−xK_x(Zn_1−yMn_y)₂As₂ studied by soft x-ray angle-resolved photoemission spectroscopy"
  H. Suzuki, G. Q. Zhao, K. Zhao, B. J. Chen, M. Horio, K. Koshiishi, J. Xu, M. Kobayashi, M. Minohara, E. Sakai, K. Horiba, H. Kumigashira, Bo Gu, S. Maekawa, Y. J. Uemura, C. Q. Jin, and A. Fujimori
  Phys. Rev. B, 92 (2015) 235120.
• "Low dimensionalization of magnetic ordering in Sr₂VO₄ by hydride ion substitution"
  Joonho Bang, Satoru Matsuishi, Sachiko Maki, Jun-ichi Yamaura, Masatoshi Hiraishi, Soshi Takeshita, Ichihiro Yamauchi, Kenji M. Kojima, and Hideo Hosono
  Phys. Rev. B, 92 (2015) 064414.
• "Origin of the anomalous mass renormalization in metallic quantum well states of strongly correlated oxide SrVO₃"
  Masaki Kobayashi, Kohei Yoshimatsu, Enju Sakai, Miho Kitamura, Koji Horiba, Atsushi Fujimori, and Hiroshi Kumigashira
  Phys. Rev. Lett., 115 (2015) 076801.
• "One-Third Magnetization Plateau with a Preceding Novel Phase in Volborthite"
  H. Ishikawa, M. Yoshida, K. Nawa, M. Jeong, S. Kramer, M. Horvatic, C. Berthier, M. Takigawa, M. Akaki, A. Miyake, M. Tokunaga, K. Kindo, J. Yamaura, Y. Okamoto, and Z. Hiroi
  Phys. Rev. Lett., 114 (2015) 227202.
• "Electronic structure for b-axis orientated of VO₂ thin film with mixed-valent state by soft X-ray spectroscopy"
  Takaaki Suetsugu, Yuichi Shimazu, Takashi Tsuchiya, Masaki Kobayashi, Enju Sakai, Hiroshi Kumigashira, and Tohru Higuchi
  J. Phys. Soc. Jpn., 84 (2015) 064715.
• "Metal-Insulator Transition of c-Axis-Controlled V₂O₃ Thin Film"
  Yuichi Shimazu, Teppei Okumura, Takashi Tsuchiya, Atsushi Shimada, Kenji Tanabe, Kazuyasu Tokiwa, Masaki Kobayashi, Koji Horiba, Hiroshi Kumigashira, and Tohru Higuchi
  J. Phys. Soc. Jpn., 84 (2015) 064701.
• "Electronic Structure of Ti_1-xFe_xO_2-δ Thin Films with Oxygen Vacancies Probed by Soft X-Ray Spectroscopy"
  Katsuya Usui, Shohei Yamaguchi, Naoya Suzuki, Yuichi Shimazu, Takashi Tsuchiya, Enju Sakai, Masaki Kobayashi, Koji Horiba, Hiroshi Kumigashira, and Tohru Higuchi
  Jpn. J. Appl. Phys., 54 (2015) 06FJ07.
• "Electronic structure and oxygen ion conductivity of as-deposited Ce_0.90Sm_0.10O_2-δ thin film prepared by RF magnetron sputtering"
  Tohru Higuchi, Tomohiro Owaku, Yasutaka Iida, Enju Sakai, Masaki Kobayashi and Hiroshi Kumigashira
  Jpn. J. Appl. Phys., 54 (2015) 06FJ04.
• "Proton conduction of BaCe_0.90Y_0.10O_3-δ Thin Film with lattice distortion"
  Shohei Yamaguchi, Yuji Tasaki, Masaki Kobayashi, Koji Horiba, Hiroshi Kumigashira, and Tohru Higuchi
  Solid State Ionics, 270 (2015) 1.
• "Enhanced Electrical Transparency by Ultra-Thin LaAlO₃ Insertion at Oxide Metal/Semiconductor Heterointerfaces"
  Takeaki Yajima, Makoto Minohara, Christopher Bell, Hiroshi Kumigashira, Masaharu Oshima, Harold Y. Hwang, and Yasuyuki Hikita
  Nano Lett., 15 (2015) 1622.
• "Controlling band alignments by artificial interface dipoles at perovskite heterointerfaces"
  Takeaki Yajima, Yasuyuki Hikita, Makoto Minohara, Christopher Bell, Julia A. Mundy, Lena F. Kourkoutis, David A. Muller, Hiroshi Kumigashira, Masaharu Oshima, and Harold Y. Hwang
  Nature Communications, 6 (2015) 6759.
• "Synthesis and magnetic properties of double-perovskite oxide La₂MnFeO₆ thin films"
  K. Yoshimatsu, K. Nogami, K. Watarai, K. Horiba, H. Kumigashira, O. Sakata, T. Oshima, and A. Ohtomo
  Phys. Rev. B, 91 (2015) 054421.
• "Direct growth of metallic TiH₂ thin films by pulsed laser deposition"
  Kohei Yoshimatsu, Takayuki Suzuki, Nobuo Tsuchimine, Koji Horiba, Hiroshi Kumigashira, Takayoshi Oshima, and Akira Ohtomo
  Appl. Phys. Exp. 8 (2015) 035801.
• "Determination of band diagram for a p-n junction between Mott insulator LaMnO₃ and band insulator Nb:SrTiO₃"
  M. Kitamura, M. Kobayashi, E. Sakai, R. Takahashi, M. Lippmaa, K. Horiba, H. Fujioka, and H. Kumigashira
  Appl. Phys. Lett. 106 (2015) 061605.
• "Electronic Structure and Photoelectrochemical Properties of an Ir-Doped SrTiO₃ Photocatalyst"
  Seiji Kawasaki, Ryota Takahashi, Kazuto Akagi, Jun Yoshinobu, Fumio Komori, Koji Horiba, Hiroshi Kumigashira, Katsuya Iwashina, Akihiko Kudo, and Mikk Lippmaa
  J. Phys. Chem. C 118 (2014) 20222.
• "Hydrogen Ordering and New Polymorph of Layered Perovskite Oxyhydrides: Sr₂VO_4-xH_x"
  Joonho Bang, Satoru Matsuishi, Haruhiro Hiraka, Fumika Fujisaki, Toshiya Otomo, Sachiko Maki, Jun-ichi Yamaura, Reiji Kumai, Youichi Murakami, and Hideo Hosono
  J. Am. Chem. Soc. 136 (2014) 7221.
• "Electronic structure of V₂O₃ thin film prepared by RF magnetron sputtering using oxygen radical and V-metal"
  Yuichi Shimazu, Teppei Okumura, Atsushi Shimada, Kenji Tanabe, Kazuyasu Tokiwa, Enju Sakai, Hiroshi Kumigashira, and Tohru Higuchi
  Jpn. J. Appl. Phys. 53 (2014) 06JG05.
• "Electrical conductivity of Sc-doped TiO₂ thin film prepared by RF magnetron sputtering"
  Tomohiro Inoue, Teppei Okumura, Yuichi Shimazu, Enju Sakai, Hiroshi Kumigashira, and Tohru Higuchi
  Jpn. J. Appl. Phys. 53 (2014) 06JG03.
• "Bandwidth-controlled metal-insulator transition in epitaxial PrNiO₃ ultrathin films induced by dimensional crossover"
  Enju Sakai, Kohei Yoshimatsu, Masatomo Tamamitsu, Koji Horiba, Atsushi Fujimori, Masaharu Oshima, and Hiroshi Kumigashira
  Appl. Phys. Lett., 104 (2014) 171609.
• "Bipartite magnetic parent phases in the iron oxypnictide superconductor"
  M. Hiraishi, S. Iimura, K.M. Kojima, J. Yamaura, H. Hiraka, K. Ikeda, P. Miao, Y. Ishikawa, S. Torii, M. Miyazaki, I. Yamauchi, A. Koda, K. Ishii, M. Yoshida, J. Mizuki, R. Kadono, R. Kumai, T. Kamiyama, T. Otomo, Y. Murakami, S. Matsuishi and H. Hosono
  Nature Physics, 10 (2014) 300.
• "Epitaxial Synthesis and Electronic Properties of Double-Perovskite Sr₂TiRuO₆ Films"
  K. Nogami, K. Yoshimatsu, H. Mashiko, E. Sakai, H. Kumigashira, O. Sakata, T. Oshima, and A. Ohtomo
  Applied Physics Express, 6 (2013) 105502.