Researcher Profile and Settings

researchmap

https://researchmap.jp/hirotoohta

Research Areas

• Natural sciences / Magnetism, superconductivity, and strongly correlated systems

Published Papers

• Synthesis and Magnetism of <i>X</i>₂Co₁₂P₇ (<i>X</i> = Group 3~5 Elements) with Zr₂Fe₁₂P₇-type Structure
  Kojiro TAKAHASHI; Hiroto OHTA; Masaki KATO
  Journal of the Japan Society of Powder and Powder Metallurgy, Japan Society of Powder and Powder Metallurgy, 71(11) 547 - 550, 15 Nov. 2024, Scientific journal
  

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• Elemental Substitution Effect and Physical Properties of Metallic Oxides La₅SrCu₆O_15−δ
  Min LI; Hiroto OHTA; Masaki KATO
  Journal of the Japan Society of Powder and Powder Metallurgy, Japan Society of Powder and Powder Metallurgy, 71(11) 534 - 537, 15 Nov. 2024, Scientific journal
  

  URLDOI URL
• Pressure-Induced Superconductivity in La₄Ni₃O_10+δ (δ = 0.04 and −0.01)
  Hibiki Nagata; Hiroya Sakurai; Yuta Ueki; Kazuki Yamane; Ryo Matsumoto; Kensei Terashima; Keisuke Hirose; Hiroto Ohta; Masaki Kato; Yoshihiko Takano
  Journal of the Physical Society of Japan, Physical Society of Japan, 93(9), 15 Sep. 2024, Scientific journal
  

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• Theoretical analysis on the possibility of superconductivity in the trilayer Ruddlesden-Popper nickelate La₄Ni₃O₁₀ under pressure and its experimental examination: Comparison with La₃Ni₂O₇
  Hirofumi Sakakibara; Masayuki Ochi; Hibiki Nagata; Yuta Ueki; Hiroya Sakurai; Ryo Matsumoto; Kensei Terashima; Keisuke Hirose; Hiroto Ohta; Masaki Kato; Yoshihiko Takano; Kazuhiko Kuroki
  PHYSICAL REVIEW B, 109 144511 , Apr. 2024
  

  DOI URL
• Site-selective cobalt substitution in La–Co co-substituted magnetoplumbite-type ferrites: ⁵⁹Co-NMR and DFT calculation study
  Hiroyuki Nakamura; Hiroto Ohta; Ryuya Kobayashi; Takeshi Waki; Yoshikazu Tabata; Hidekazu Ikeno; Christian Méry
  Journal of Physics: Materials, 7 025012 , Apr. 2024
  

  DOI URL
• A new double-layered kagome antiferromagnet ScFe₆Ge₄
  Mohamed Abdelkareem Kassem; Taiki Shiotani; Hiroto Ohta; Yoshikazu Tabata; Takeshi Waki; Hiroyuki Nakamura
  Solid State Communications, 385 115513 , Mar. 2024
  

  DOI URL
• Emergent strong ferromagnetism in site-ordered Laves phase YMgCo₄
  T. Shiotani; H. Ohta; T. Waki; Y. Hashimoto; Y. Tabata; H. Nakamura
  Journal of Alloys and Compounds, 961 170990 , Jul. 2023
  

  DOI URL
• Magnetic-field-induced valence change in Eu(Co_1-xNi_x)₂P₂ up to 60 T
  Raito Nakamura; Azumi Ishita; Jin Nakamura; Hiroto Ohta; Yuya Haraguchi; Hiroko Aruga Katori; Hajime Ishikawa; Akira Matsuo; Koichi Kindo; Minoru Nohara; Akihiko Ikeda
  Physical Review B, American Physical Society (APS), 107(23) 235110 , 05 Jun. 2023, Scientific journal
  

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• The internal magnetic field in a ferromagnetic compound Y₂Co₁₂P₇
  Kazuki Ohishi; Hiroto Ohta; Yusuke Kato; Hiroko Aruga Katori; Ola K. Forslund; Elisabetta Nocerino; Nami Matsubara; Papadopoulos Konstantinos; Fredrik O. L. Johansson; Yasmine Sassa; Martin Månsson; Bassam Hitti; Donald Arseneau; Gerald D. Morris; Jess H. Brewer; Jun Sugiyama
  Journal of Physics: Conference Series, IOP Publishing, 2462(1) 012008 - 012008, 01 Mar. 2023, Scientific journal
  

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• Study on Site Preference and Electronic State of Y₂(Mn_xFe_1−x)₁₂P₇ with the Zr₂Fe₁₂P₇-type Structure
  Taiki SHIOTANI; Hiroto OHTA; Takeshi WAKI; Yoshikazu TABATA; Hiroyuki NAKAMURA
  Journal of the Japan Society of Powder and Powder Metallurgy, Japan Society of Powder and Powder Metallurgy, 69(11) 461 - 466, 15 Nov. 2022, Scientific journal
  

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• Study on Factors Hindering the Single-phase Formation of Divalent-ion-stabilized W-type Ferrites
  Shinji NAKAI; Takeshi WAKI; Yoshikazu TABATA; Masaki KATO; Hiroto OHTA; Hiroyuki NAKAMURA
  Journal of the Japan Society of Powder and Powder Metallurgy, Japan Society of Powder and Powder Metallurgy, 69(11) 455 - 460, 15 Nov. 2022, Scientific journal
  

  URLDOI URL
• Sinusoidal Magnetic Structure of Andalusite-type Al_xFe_2−xGeO₅ with x = 0.09 and 0.15
  Kazuo Kakimoto; Hiroto Ohta; Yuya Haraguchi; Masato Hagihala; Shuki Torii; Takashi Kamiyama; Hiroko Aruga Katori
  Journal of the Physical Society of Japan, Physical Society of Japan, 91(5), 15 May 2022, Scientific journal
  

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• Magnetism of Al_xFe_2−xGeO₅ with Andalusite Structure
  Kazuo Kakimoto; Saki Takada; Hiroto Ohta; Yuya Haraguchi; Masato Hagihala; Shuki Torii; Takashi Kamiyama; Hiroyuki Mitamura; Masashi Tokunaga; Atsushi Hatakeyama; Hiroko Aruga Katori
  Journal of the Physical Society of Japan, Physical Society of Japan, 91(5), 15 May 2022, Scientific journal
  

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• Single-Crystal Growth of (Ca_1-xMg_x)₂Co₁₂P₇ and its Itinerant-Electron Magnetism
  Kohei YOSHINAGA; Kensuke NARA; Kodai MORIYAMA; Chishiro MICHIOKA; Hiroaki UEDA; Hiroto OHTA; Kazuyoshi YOSHIMURA
  Journal of the Japan Society of Powder and Powder Metallurgy, Japan Society of Powder and Powder Metallurgy, 69(4) 155 - 159, 15 Apr. 2022, Scientific journal
  

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• Magnetic Properties of Eu(Co_1−xNi_x)₂P₂
  Raito Nakamura; Hiroto Ohta; Yoshio Kobayashi; Yuya Haraguchi; Hiroko Aruga Katori; Jin Nakamura
  Journal of the Physical Society of Japan, Physical Society of Japan, 91(2), 15 Feb. 2022, Scientific journal
  

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• Co-existence of short- and long-range magnetic order in LaCo₂P₂
  Ola Kenji Forslund; Daniel Andreica; Hiroto Ohta; Masaki Imai; Chishiro Michioka; Kazuyoshi Yoshimura; Martin Månsson; Jun Sugiyama
  Physica Scripta, IOP Publishing, 24 Nov. 2021, Scientific journal
  

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• Pressure dependence of ferromagnetic phase boundary in BaVSe₃ studied with high-pressure μ⁺SR
  Jun Sugiyama; Wataru Higemoto; Daniel Andreica; Ola Kenji Forslund; Elisabetta Nocerino; Martin Månsson; Yasmine Sassa; Ritu Gupta; Rustem Khasanov; Hiroto Ohta; Hiroyuki Nakamura
  Physical Review B, American Physical Society (APS), 103(10), 12 Mar. 2021, Scientific journal
  

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• Revisiting the A -type antiferromagnet NaNiO₂ with muon spin rotation measurements and density functional theory calculations
  Ola Kenji Forslund; Hiroto Ohta; Kazuya Kamazawa; Scott L. Stubbs; Oren Ofer; Martin Månsson; Chishiro Michioka; Kazuyoshi Yoshimura; Bassam Hitti; Donald Arseneau; Gerald D. Morris; Eduardo J. Ansaldo; Jess H. Brewer; Jun Sugiyama
  Physical Review B, American Physical Society (APS), 102(18), 11 Nov. 2020, Scientific journal
  

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• Magnetocaloric study of Ln₂Co₁₂P₇ (Ln = Y, Nd, and Sm)
  Hiroto Ohta; Yusuke Kato; Yusuke Watanabe; Hiroko Aruga Katori; Naohito Tsujii; Naoki Kikugawa; Hiroya Sakurai
  Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy, 67(2) 97 - 99, 2020, Scientific journal
  

  DOI URLScopus URLScopus Citedby URL
• Study on Magnetism and Electronic Structure of New Layered Compound Sr₃ScO₅Co₂As₂ with Body-Centered Crystal Structure
  Hiroto Ohta; Atsushi Suzuki; Hiroko Aruga Katori
  Journal of the Physical Society of Japan, 88 054714-1 - 6, Apr. 2019, Scientific journal
• Magnetic Study on Y₂M₃Co₉P₇ (M: Transition Metals) with Cation-Ordered Zr₂Fe₁₂P₇-Type Structure
  Yusuke Kato; Hiroto Ohta; Hiroko Aruga Katori
  Solid State Phenomena, 289 164 - 169, Apr. 2019, International conference proceedings
• Disappearance of the Itinerant Electronic Ferromagnetism in Layered Compound Sr₂VO₃CoAs due to Self-Electron-Doping Effect
  Hiroto Ohta; Daisuke Noguchi; Hiroko Aruga Katori
  Journal of the Physical Society of Japan, 87 094711-1 - 6, Aug. 2018, Scientific journal
• Magnetism and electronic states of X₂Co₁₂P₇ (X = Ti, Zr and Hf)
  Yusuke Kato; Hiroto Ohta; Hiroko Aruga Katori
  Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy, Journal of the Japan Society of Powder and Powder Metallurgy, 65(5) 274 - 278, 2018, International conference proceedings
  

  DOI URL
• Physical properties of the layered compounds RE₃Ru₄Al₁₂ (RE = La-Nd)
  Wanyin Ge; Chishiro Michioka; Hiroto Ohta; Kazuyoshi Yoshimura
  SOLID STATE COMMUNICATIONS, 195 1 - 5, Oct. 2014, Scientific journal
  

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• Successive magnetic transitions in RECoAsO
  Sugiyama Jun; Mansson Martin; Kamazawa Kazuya; Harada Masashi; Ofer Oren; Andreica Daniel; Amato Alex; Brewer Jess H; Ansaldo Eduardo J; Ohta Hiroto; Michioka Chishiro; Yoshimura Kazuyoshi; Luke GM; Sonier J
  12th International Conference on Muon Spin Rotation, Relaxation and Resonance (Musr2011), 30 262 - 265, 2012
  

  DOI URL
• Magnetic nature of water intercalated Na0.35CoO2
  Sugiyama Jun; Ikedo Yutaka; Mansson Martin; Ofer Oren; Ansaldo Eduardo J; Brewer Jess H; Chow Kim H; Lord James S; Ohta Hiroto; Michioka Chishiro; Yoshimura Kazuyoshi; Luke GM; Sonier J
  12th International Conference on Muon Spin Rotation, Relaxation and Resonance (Musr2011), 30 266 - 270, 2012
  

  DOI URL
• Spin fluctuations on the verge of a ferromagnetic quantum phase transition in Ni3Al1-xGax
  Jinhu Yang; Bin Chen; Hiroto Ohta; Chishiro Michioka; Kazuyoshi Yoshimura; Hangdong Wang; Minghu Fang
  PHYSICAL REVIEW B, 83(13) 134433/1 - 9, Apr. 2011, Scientific journal
  

  DOI URL
• Magnetic study of SmCoAsO showing a ferromagnetic-antiferromagnetic transition
  Hiroto Ohta; Chishiro Michioka; Akira Matsuo; Koichi Kindo; Kazuyoshi Yoshimura
  Physical Review B - Condensed Matter and Materials Physics, 82(5), 16 Aug. 2010, Scientific journal
  

  DOI URL
• Synthesis and magnetic properties of the layered compound Fe 3GeTe2
  Bin Chen; JinHu Yang; Hiroto Ohta; Chishiro Michioka; Kazuyoshi Yoshimura
  Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy, 57(3) 172 - 176, Mar. 2010, Scientific journal
  

  DOI URL
• Study of magnetic properties of layered compound LaCoAsO and its related compounds
  Hiroto Ohta; Bin Chen; Jinfu Yang; Chishiro Michioka; Kazuyoshi Yoshimura
  Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy, 57(3) 177 - 180, Mar. 2010, Scientific journal
  

  DOI URL
• Anomalous magnetization in the layered itinerant ferromagnet LaCoAsO
  Hiroto Ohta; Kazuyoshi Yoshimura
  Physical Review B - Condensed Matter and Materials Physics, 79(18), 06 May 2009, Scientific journal
  

  DOI URL

MISC

• Itinerant Magnetism Research for the Single Crystals of Ca₂(Fe_xCo_1-x)₁₂P₇
  吉永公平; 森山広大; 道岡千城; 植田浩明; 太田寛人; 香取浩子; 吉村一良
  日本物理学会講演概要集(CD-ROM), 77(1), 2022
• μ⁺SR study on R₂Co₁₂P₇
  杉山純; 大石一城; 太田寛人; 加藤優典; 香取浩子; MORRIS Gerald D.; HITTI Bassam; ARSENEAU Donald; FORSLUND Ola K.; NOCERINO Elisabetta; PAPADOPOULOS Konstantinos; SASSA Yasmine; MANSSON Martin
  日本物理学会講演概要集(CD-ROM), 76(1), 2021
• (Mg_xCa_1-x)₂Co₁₂P₇の単結晶を用いた遍歴電子磁性研究
  吉永公平; 奈良建佑; 森山広大; 道岡千城; 植田浩明; 吉村一良; 太田寛人; 香取浩子
  粉体粉末冶金協会講演大会(Web), 2021, 2021
• Study on magnetic structure of andalusite structure Al_xFe_2-xGeO₅ (x = 0.15, 0.2)
  柿本和勇; 太田寛人; 原口祐哉; 萩原雅人; 鳥居周輝; 神山崇; 畠山温; 香取浩子
  日本物理学会講演概要集(CD-ROM), 76(1), 2021
• Structure and magnetism of intermediate valence compound Eu(Co_1-xNi_x)₂P₂
  中村頼人; 太田寛人; 原口祐哉; 香取浩子; 松尾晶; 金道浩一; 中村仁
  日本物理学会講演概要集(CD-ROM), 76(1), 2021
• ¹⁵¹Eu Moessbauer spectroscopy of mixed valence compound Eu(Co_1-xNi_x)₂P₂
  中村頼人; 太田寛人; 原口祐哉; 香取浩子; 松尾晶; 金道浩一; 小林義男; 中村仁
  日本物理学会講演概要集(CD-ROM), 76(2), 2021
• Synthesis and magnetism of ordered Zr₂Fe₁₂P₇-type compound Y₂Tm^py₃Tm^tet₉P₇ (Tm^py, Tm^tet: transition metals)
  太田寛人; 須賀隆裕; 加藤優典; 和氣剛; 田畑吉計; 香取浩子; 中村裕之
  日本物理学会講演概要集(CD-ROM), 75(1), 2020
• Itinerant electric magnetism of single-crystalline Ca₂Co₁₂P₇: II
  奈良建佑; 森山広大; 村川譲一; 道岡千城; 植田浩明; 太田寛人; 香取浩子; 吉村一良
  日本物理学会講演概要集(CD-ROM), 75(1), 2020
• (Ca_1-xMg_x)₂Co₁₂P₇の単結晶を用いた遍歴電子磁性研究
  奈良建佑; 森山広大; 村川譲一; 道岡千城; 植田浩明; 太田寛人; 香取浩子; 吉村一良
  京都大学物性科学センター誌, (36), 2020
• Itinerant-electron magnetism of (Ca_1-xMg_x)₂Co₁₂P₇
  奈良建佑; 森山広大; 村川譲一; 道岡千城; 植田浩明; 太田寛人; 香取浩子; 吉村一良
  日本物理学会講演概要集(CD-ROM), 75(2), 2020
• Study of magnetic structure by neutron powder diffraction on andalusite phase Al_xFe_2-xGeO₅
  柿本和勇; 柿本和勇; 太田寛人; 原口祐哉; 萩原雅人; 鳥居周輝; 神山崇; 香取浩子
  日本物理学会講演概要集(CD-ROM), 75(1), 2020
• Magnetic properties of Eu(Co_1-xNi_x)₂P₂ in ucT and cT structures
  中村頼人; 太田寛人; 原口祐哉; 香取浩子; 中村仁
  日本物理学会講演概要集(CD-ROM), 75(1), 2020
• 遍歴強磁性体Y₂Co₁₂P₇の元素置換効果の研究
  太田寛人; 加藤優典; 香取浩子; 中村真一; 中村真一; 勝藤拓郎
  粉体粉末冶金協会講演大会(Web), 2019, 2019
• A₂Co₁₂P₇(A=Mg,Ca)の単結晶育成と遍歴電子磁性
  奈良建佑; 森山広大; 村川譲一; 道岡千城; 植田浩明; 吉村一良; 太田寛人; 香取浩子
  粉体粉末冶金協会講演大会(Web), 2019, 2019
• 遍歴電子強磁性体Y₂(Fe_xCo_1-x)₁₂P₇の⁵⁷Feメスバウアー分光による磁気秩序状態の研究
  太田寛人; 中村真一; 中村真一; 加藤優典; 香取浩子; 勝藤拓郎
  日本物理学会講演概要集(CD-ROM), 74(1), 2019
• Ca₂Co₁₂P₇の単結晶を用いた遍歴電子磁性研究
  奈良建佑; 森山広大; 村川譲一; 道岡千城; 植田浩明; 太田寛人; 香取浩子; 吉村一良
  日本物理学会講演概要集(CD-ROM), 74(1), 2019
• 磁気モーメントを持つSillimanite相M₂GeO₅の探索
  柿本和勇; 高田早紀; 太田寛人; 香取浩子
  日本物理学会講演概要集(CD-ROM), 74(1), 2019
• (Ca_1-xMg_x)₂Co₁₂P₇の単結晶育成と遍歴電子磁性
  奈良建佑; 森山広大; 村川譲一; 道岡千城; 植田浩明; 吉村一良; 太田寛人; 香取浩子
  粉体粉末冶金協会講演大会(Web), 2019, 2019
• (Ca_1-xMg_x)₂Co₁₂P₇の単結晶を用いた遍歴電子磁性研究
  奈良建佑; 森山広大; 村川譲一; 道岡千城; 植田浩明; 太田寛人; 香取浩子; 吉村一良
  日本物理学会講演概要集(CD-ROM), 74(2), 2019
• EuCo₂P₂のNi置換による磁性の研究
  中村頼人; 太田寛人; 原口祐哉; 香取浩子; 中村仁
  日本物理学会講演概要集(CD-ROM), 74(2), 2019
• 遍歴電子強磁性体Y₂Co₁₂P₇の電子状態と磁性の研究
  太田寛人; 加藤優典; 原口祐哉; 香取浩子
  日本物理学会講演概要集(CD-ROM), 74(2), 2019
• 遍歴電子強磁性体X₂Co₁₂P₇(X=Zr,Hf)のFe置換効果と磁性の研究
  太田寛人; 中村真一; 中村真一; 加藤優典; 原口祐哉; 香取浩子; 勝藤拓郎
  日本物理学会講演概要集(CD-ROM), 74(2), 2019
• 鉄梯子格子化合物Ba₆Fe₈S₁₅の磁気秩序状態における電子状態の研究
  太田寛人; 本田孝志; 中村真一; 中村真一; 濱住莉加; 香取浩子; 大友季哉; 勝藤拓郎
  日本物理学会講演概要集(CD-ROM), 73(2) ROMBUNNO.10aPS‐30 , 21 Sep. 2018
  

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• 逆スピネル化合物Mn_2-xZn_xXO₄(X=Sn,Ti)の構造と磁性の研究
  行田祥一郎; 太田寛人; 香取浩子
  日本物理学会講演概要集(CD-ROM), 73(1), 2018
• 遍歴電子強磁性体Ln₂Co₁₂As₇(Ln=lanthanoids)の構造と磁性
  加藤優典; 太田寛人; 香取浩子; 三田村裕幸; 三宅厚志; 徳永将史
  日本物理学会講演概要集(CD-ROM), 73(1), 2018
• 逆スピネルCo₂XO₄(X=Ti,Sn)の非磁性元素部分置換による磁性の研究
  太田寛人; 高田早紀; 徳永柊介; 上田元気; 香取浩子
  日本物理学会講演概要集(CD-ROM), 73(1), 2018
• T_xM_2-xGeO₅(T=Al,Ga,M=V,Cr,Fe)における相図と磁性の研究
  高田早紀; 太田寛人; 香取浩子; 三田村裕幸; 三宅厚志; 徳永将史
  日本物理学会講演概要集(CD-ROM), 73(1), 2018
• Andalusite構造を持つGa_xFe_2-xGeO₅における磁性の研究
  柿本和勇; 高田早紀; 太田寛人; 香取浩子
  日本物理学会講演概要集(CD-ROM), 73(1), 2018
• 遍歴電子強磁性体Y₂(Fe,Co)₁₂P₇のメスバウアー分光による構造と磁性の研究
  太田寛人; 中村真一; 中村真一; 加藤優典; 香取浩子; 勝藤拓郎
  日本物理学会講演概要集(CD-ROM), 73(2), 2018
• 多形化合物Fe_2-xAl_xGeO₅のメスバウアー分光を用いた構造と磁性の研究
  太田寛人; 中村真一; 中村真一; 高田早紀; 香取浩子; 勝藤拓郎
  日本物理学会講演概要集(CD-ROM), 73(2), 2018
• 梯子格子化合物Ba₆Fe₈S₁₅の構造解析
  太田寛人; 足立貴弘; 香取浩子; 佐賀山基; 熊井玲児; 村上洋一
  KEK Progress Report (Web), (2016-8), 2017
• 単結晶を用いた逆スピネルCo₂XO₄(X=Ti,Sn)のZn部分置換系の磁気的研究
  太田寛人; 高田早紀; 上田元気; 香取浩子
  日本物理学会講演概要集(CD-ROM), 72(1), 2017
• Andalusite構造を持つ(Al_xFe_2-x)GeO₅における磁性の研究
  高田早紀; 太田寛人; 香取浩子; 三宅厚志; 徳永将史
  日本物理学会講演概要集(CD-ROM), 72(1), 2017
• 遍歴電子強磁性体Ln₂Co₁₂P₇(Ln=lanthanoid)の磁性およびLn-Co間相互作用の研究
  加藤優典; 太田寛人; 香取浩子; 三宅厚志; 徳永将史
  日本物理学会講演概要集(CD-ROM), 72(1), 2017
• Ge_xFe_3-xO₄(0≦x≦1)の保磁力に対する磁気凍結の影響の研究
  磯崎勝哉; 太田寛人; 香取浩子; 山本明保; 植田大地; 吉田雅洋; 吉沢英樹; 三宅厚志; 徳永将史
  日本物理学会講演概要集(CD-ROM), 72(1), 2017
• CoAs層を有する層状化合物の局所的構造と磁性の関係の研究
  鈴木敦; 太田寛人; 香取浩子
  日本物理学会講演概要集(CD-ROM), 72(1), 2017
• 遍歴強磁性体A₂Co₁₂P₇(A=Ca,Y,Zr)の選択的元素置換効果
  加藤優典; 太田寛人; 香取浩子
  日本物理学会講演概要集(CD-ROM), 72(2), 2017
• 多形(Al_xFe_2-x)GeO₅における状態図と磁性の研究
  高田早紀; 太田寛人; 香取浩子
  日本物理学会講演概要集(CD-ROM), 72(2), 2017
• 逆スピネル化合物Co₂XO₄(X=Ti,Sn)のMg部分置換による研究
  太田寛人; 香取浩子
  日本物理学会講演概要集(CD-ROM), 72(2), 2017
• CoAs層を含む新規層状化合物Sr₃Sc₂O₅Co₂As₂の磁性
  鈴木敦; 太田寛人; 香取浩子
  日本物理学会講演概要集(CD-ROM), 71(1), 2016
• 鉄梯子格子化合物Ba₆Fe₈S₁₅の構造と磁気秩序
  太田寛人; 足立貴弘; 香取浩子; 佐賀山基; 熊井玲児; 村上洋一; 中村真一; 中村真一; 不破章雄
  日本物理学会講演概要集(CD-ROM), 71(1), 2016
• ⁷⁵As-NMR study of Cr based antiperovskite type nitride Cr₃AsN
  Takao K; Waki T; Ohta H; Yajima T; Hiroi Z; Tabata Y; Nakamura H
  Meeting Abstracts of the Physical Society of Japan, The Physical Society of Japan, 71(0) 750 - 750, 2016
  

  DOI URL
• 層状化合物Ae₂ScO₃CoPの磁性
  太田寛人; 伊土将平; 香取浩子
  粉体粉末冶金協会講演概要集, 2015, 2015
• 層状化合物ACoPn(A=Na,Cu;Pn=P,As)の合成と磁性
  幸村健介; 太田寛人; 香取浩子
  日本物理学会講演概要集(CD-ROM), 70(1), 2015
• 高保磁力層状コバルト水酸化物の磁性と構造
  穴井克樹; 中村哲也; 萩原政幸; 木田孝則; 奥谷顕; 香取浩子; 太田寛人; 酒井政道; 福田武司; 鎌田憲彦; 本多善太郎
  応用物理学会春季学術講演会講演予稿集(CD-ROM), 62nd, 2015
• 21aPS-72 Magnetism of Cr based antiperovskite type nitrides
  Takao K; Liu Z; Uji K; Ohta H; Waki T; Tabata Y; Watanabe I; Nakamura H
  Meeting Abstracts of the Physical Society of Japan, The Physical Society of Japan, 70(0) 1005 - 1005, 2015
  

  DOI URL
• 7aPS-90 High-field magnetism of the layered cobalt compounds Co_2(OH)_2(X)(X=TPA, NDCA, SDCA)
  Okutani A.; Honda Z.; Katori H.; Ohta H.; Hagiwara M.
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 69(2) 252 - 252, 22 Aug. 2014
• 7pBJ-9 Semiconducting behavior and magnetic properties of tetragonal Yb_2MgSi_2
  Numakura R.; Kosaka M.; Michimura S.; Katano S.; Nakajima D.; Nonaka R.; Wakabayashi Y.; Terashima T.; Ohta H.; Katori H. A.
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 69(2) 342 - 342, 22 Aug. 2014
• 8pBC-7 Low-dimensional magnetism in Fe-based ladder compound Ba_6Fe_8S_<15>
  Adachi T.; Ohta H.; Aruga Katori H.
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 69(2) 295 - 295, 22 Aug. 2014
• 7aPS-85 Ferromagnetic-Antiferromagnetic transition in ternary compounds Ln_2Co_<12>P_7 (Ln:lanthanoid)
  Watanabe Y.; Ohta H.; Aruga Katori H.
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 69(2) 251 - 251, 22 Aug. 2014
• 7aPS-78 Search for new magnetic compounds with Sr_2Mn_3As_2O_2-type structure
  Ohta Hiroto; Takeno Mizuki; Noguchi Daisuke; Aruga Katori Hiroko
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 69(2) 249 - 249, 22 Aug. 2014
• 7aPS-79 Relationship between low dimensionality and magnetism in itinerant-electronic magnet AeCo_2As_2(Ae=Ca,Sr,Ba)
  Akabane E.; Ohta H.; Noguchi D.; Aruga Katori H.
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 69(2) 249 - 249, 22 Aug. 2014
• 27aPS-38 Physical properties of an itinerant-electron metamagnetic compound SrCo_2P_2 and substituted compounds
  IMAI Masaki; MICHIOKA Chishiro; UEDA Hiroaki; OHTA Hiroto; MATSUO Akira; KINDO Koichi; YOSHIMURA Kazuyoshi
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 69(1) 483 - 483, 05 Mar. 2014
• 29pAS-1 Electronic structure and magnetism of layered compound Sr_2VO_3CoAs
  Ohta Hiroto; Noguchi Daisuke; Aruga Katori Hiroko
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 69(1) 528 - 528, 05 Mar. 2014
• 29pAS-2 Relationship between structure and magnetism in itinerant-electronic magnet AeCo_2As_2
  Akabane E.; Ohta H.; Noguchi D.; Aruga Katori H.
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 69(1) 528 - 528, 05 Mar. 2014
• 27pAF-6 Synthesis and magnetism in Spinel compound Mn_2SnO_4
  Ueda G.; Imai Y.; Ohta H.; Aruga Katori H.
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 69(1) 508 - 508, 05 Mar. 2014
• 27pAF-5 Synthesis and magnetic properties of quasi-one-dimensional screw chain compound PbCo_<2-x>Mn_xV_2O_8
  Saito Daichi; Ohta Hiroto; Katori Aruga
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 69(1) 508 - 508, 05 Mar. 2014
• Fe梯子格子を含む化合物Ba₆Fe₈S₁₅の低次元磁性
  足立貴弘; 太田寛人; 香取浩子
  日本物理学会講演概要集, 69(2), 2014
• 三元系化合物Ln₂Co₁₂P₇(Ln:ランタノイド)の強磁性-反強磁性転移
  渡辺悠介; 太田寛人; 香取浩子
  日本物理学会講演概要集, 69(2), 2014
• Effects of Sc ion substitution with V ion and physical properties of itinerant ferromagnet Sr_2ScO_3CoAs
  Noguchi D.; Ohta H.; Aruga Katori H.
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 68(2) 376 - 376, 26 Aug. 2013
• NMR study of an itinerant-electron metamagnetic system Sr_<1-x>Ca_xCo_2P_2
  IMAI Masaki; MICHIOKA Chishiro; UEDA Hiroaki; OHTA Hiroto; YOSHIMURA Kazuyoshi
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 68(2) 376 - 376, 26 Aug. 2013
• Carrier doping effect on and magnetism of layered compound AeCo_2As_2
  Akabane E.; Ohta H.; Noguchi D.; Aruga Katori H.
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 68(2) 376 - 376, 26 Aug. 2013
• Magnetic anisotropy of spinel compound GeFe_2O_4 single crystal
  Ando Yuichi; Ohta Hiroto; Aruga Katori Hiroko; Tokunaga Masashi; Kosaka Masashi
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 68(2) 419 - 419, 26 Aug. 2013
• Magnetism and electric conductivity of ternary compounds Ln_2Co_<12>Pn_7
  Ohta H.; Akabane E.; Noguchi D.; Aruga Katori H.
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 68(2) 532 - 532, 26 Aug. 2013
• 28pXW-8 Physical properties of an itinerant-electron metamagnetic compound SrCo_2P_2 and its family
  IMAI Masaki; OHTA Hiroto; MATSUO Akira; KINDO Koichi; MICHIOKA Chishiro; UEDA Hiroaki; YOSHIMURA Kazuyoshi
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 68(1) 551 - 551, 26 Mar. 2013
• 29aXA-2 Magnetic properties of spinel compound GeFe_2O_4 single crystal in a magnetic field
  Ando Yuichi; Ohta Hiroto; Katori(Aruga) Hiroko
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 68(1) 556 - 556, 26 Mar. 2013
• 29aPS-121 Substitution effects of itinerant electronic ferromagnet with CoAs planes
  Ohta Hiroto; Akabane Eeisuke; Nakamura Takehito; Noguchi Daisuke; Aruga(Katori) Hiroko
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 68(1) 711 - 711, 26 Mar. 2013
• 二次元遍歴電子磁性体Ae₂MO₃CoAsの磁性
  野口大介; 太田寛人; 香取浩子
  日本物理学会講演概要集, 68(1), 2013
• Physical Properties of Itinerant Magnetic Compounds BaCo2P2
  M. Imai; H. Ohta; C. Michioka; H. Ueda; K. Yoshimura
  Proceedings of the 2012 Powder Metallurgy World Congress & Exhibition, 16F-T14-121/1-4, 2013
• Superconductivity and Itinerant Magnetism in Layered Fe- Chalcogenide and Co-Pnictide Systems
  Kazuyoshi Yoshimura; Chishiro Michioka; Hiroto Ohta
  Proceedings of the 2012 Powder Metallurgy World Congress & Exhibition, 16F-T14-19/1-8, 2013
• 18aPSA-2 Itinerant electronic ferromagnet with CoAs layer Ae_2MO_3CoAs
  Ohta Hiroto; Noguchi Daisuke; Katori Hiroko Aruga
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 67(2) 378 - 378, 24 Aug. 2012
• 18pCD-2 Synthesis and magnetic properties of spinel compound GeFe_2O_4 single crystal
  Ando Yuichi; Ohta Hiroto; Katori Hiroko Aruga
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 67(2) 397 - 397, 24 Aug. 2012
• 20pCD-1 Magnetism in itinerant ferromagnet Sr_2ScO_3CoAs
  Noguchi D.; Ohta H.; Aruga Katori H.
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 67(2) 435 - 435, 24 Aug. 2012
• 25aPS-89 Searching New Compounds in the Cobalt-pnictide System
  Ohta H.; Kimura S.; Nabetani K.; Noguchi D.; Aruga Katori H.
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 67(1) 613 - 613, 05 Mar. 2012
• 24aPS-40 Quantum Critical Behaves of Itinerant Ferromagnets Fe_<1-x>Co_xGa_3 and Fe(Ga_<1-x>Ge_x)_3
  Zhang Yao; Imai Masaki; Nawa Kazuhiro; Ohta Hiroto; Michioka Chishiro; Yoshimura Kazuyoshi; Hadano Yuta; Takabatake Toshiro
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 67(1) 484 - 484, 05 Mar. 2012
• Itinerant-Electron Metamagnetic Transition in layered (Sr-Ca)Co2P2 System
  M. Imai; C. Michioka; H. Ohta; H. Ueda; A. Matsuo; K. Kindo; K. Yoshimura
  Proceedings of the 10th International Conference on Research in High Magnetic Fields 2012, O-I-17/1-6, 2012
• Magnetic properties of itinerant ferromagnet La ₁₂Fe _57.5As ₄₁
  B. Chen; J. Yang; S. Takehara; H. Ohta; C. Michioka; K. Yoshimura
  Journal of Physics: Conference Series, 344(1), 2012
  

  DOI URL
• 22aGC-7 High Magnetic Field XMCD in a Heavy Fermion Compound YbAgCu_4
  Matsuda Y. H.; Nakamura T.; Her J. L.; Kindo K.; Michimura S.; Inami T.; Mizumaki M.; Kawamura N.; Suzuki M.; Bin C.; Ohta H.; Yoshimura K.
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 66(2) 493 - 493, 24 Aug. 2011
• 21pGL-8 Microscopic magnetic nature of RECoAsO probed by μ^+SR II
  Sugiyama J.; Kamazawa K.; Harada M.; Ohta H.; Michioka C.; Yoshimura K.; Mansson Martin; Andreica Daniel; Amato Alex; Ofer Oren; Ansaldo Eduardo J.; Brewer Jess H.
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 66(2) 487 - 487, 24 Aug. 2011
• 22pPSA-7 Physical properties of a ternary compound La_<12>Fe_<57.5>As_<41>
  Takehara S.; Chen B.; Yang J. H.; Ohta H.; Michioka C.; Yoshimura K.
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 66(2) 556 - 556, 24 Aug. 2011
• 22pPSA-9 Synthesis and physical property of layered compounds with CoPn conducting plane
  Ohta Hiroto; Michioka Chishiro; Yoshimura Kazuyoshi
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 66(2) 557 - 557, 24 Aug. 2011
• 22pGM-8 Microscopic properties of the novel quasi two-dimensional iron chalcogenide superconductors and their intercalates
  Michioka C.; Ohta H.; Amano A.; Yoshimura K.; Fang M.
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 66(2) 549 - 549, 24 Aug. 2011
• 22pPSA-12 Syntheses and physical properties of CaFe_4As_3 and surrounding compounds II
  Osada Yoshiaki; Ohta Hiroto; Michioka Chishiro; Yoshimura Kazuyoshi
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 66(2) 557 - 557, 24 Aug. 2011
• 21aPS-45 NMR Study of the Fe(Ga_<1-x>Ge_x)_3 Itinerant Ferromagnetic System
  Zhang Yao; Nawa Kazuhiro; Ohta Hiroto; Yoshimura Kazuyoshi; Hadano Yuta; Takabatake Toshiro
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 66(2) 382 - 382, 24 Aug. 2011
• 23pGL-4 High-T_c Superconductivity and Itinerant-Election Magnetism in 2D Fe(Co)-based Chalcogenide and Pnictide Systems
  Yoshimura Kazuyoshi; Michioka Chishiro; Ohta Hiroto
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 66(2) 621 - 621, 24 Aug. 2011
• 25pPSB-19 Itinerant ferromagnetism of a ternary compound La_<12>Fe<57.>As_<41>
  Takehara S.; Chen B.; Yang J.H.; Ohta H.; Michioka C.; Yoshimura K.
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 66(1) 569 - 569, 03 Mar. 2011
• 25pPSB-17 Synthesis and property of PbO-type FeTe and surrounding Compounds II
  Amano A.; Matsui M.; Kawa M.; Yang J.H.; Ohta H.; Michioka C.; Weda H.; Yoshimura K.
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 66(1) 568 - 568, 03 Mar. 2011
• 27pGW-11 NMR studies of the novel quasi two-dimensional superconducting Fe(Te-Se) system I
  Michioka C.; Ohta H.; Matsui M.; Kawa M.; Yang J.; Yoshimura K.; Fang M.
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 66(1) 643 - 643, 03 Mar. 2011
• 25pPSB-23 Synthesis and physical property of layered compounds with CoPn conducting plane
  Ohta Hiroto; Imai Masaki; Michioka Chishiro; Yoshimura Kazuyoshi
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 66(1) 570 - 570, 03 Mar. 2011
• 26aEC-6 Magnetic field induced valence transition in YbAgCu_4
  Nakamura T.; Her J.L.; Matsuda Y.H.; Kindo K.; Inami T.; Michimura S.; Mizumaki M.; Kawamura N.; Suzuki M.; Bin C.; Ohta H.; Yoshimura K.
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 66(1) 583 - 583, 03 Mar. 2011
• 25pPSB-24 Syntheses and Physical Properties of AeCo_2P_2(Ae=Ca,Sr,Ba)
  Imai Masaki; Ohta Hiroto; Michioka Chishiro; Yoshimura Kazuyoshi
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 66(1) 570 - 570, 03 Mar. 2011
• 25pPSB-22 Syntheses and physical properties of CaFe_4As_3 and surrounding compounds
  Osada Yoshiaki; Ohta Hiroto; Michioka Chishiro; Yoshimura Kazuyoshi
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 66(1) 569 - 569, 03 Mar. 2011
• 25pPSA-50 Physical Properties of Ca_3Co_2O_6 and Ca_3CoRhO_6
  Amano A.; Ohta H.; Michioka C.; Yoshimura K.
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 65(2) 441 - 441, 18 Aug. 2010
• 23aPS-140 Microscopic magnetic nature of RECoAsO probed byμ^+SR
  Sugiyama J.; Kamazawa K.; Harada M.; Ohta H.; Michioka C.; Yoshimura K.; Mansson Martin; Andreica Daniel; Amato Alex
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 65(2) 492 - 492, 18 Aug. 2010
• 23aPS-141 μ^+SR study of water-absorbed Na_xCoO_2
  Sugiyama J.; Ikedo Y.; Ohta H.; Michioka C.; Yoshimura K.; Brewer J. H.; Ansaldo E. J.; Stubbs S. L.; Chow K. H.; Mansson M.; Lord J. S.
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 65(2) 493 - 493, 18 Aug. 2010
• 23pWH-2 Magnetization, specific heat and electric resistivity of layered compounds LnCoAsO
  OHTA Hiroto; MICHIOKA Chishiro; YOSHIMURA Kazuyoshi
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 65(2) 501 - 501, 18 Aug. 2010
• 23pPSA-18 High magnetic field magnetization and valence state in YbAgCu_4
  Nakamura T.; Her J. L.; Matsuda Y. H.; Kindo K.; Inami T.; Michimura S.; Mizumaki M.; Kawamura N.; Suzuki M.; Bin C.; Ohta H.; Yoshimura K.
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 65(2) 515 - 515, 18 Aug. 2010
• 23pPSA-70 Synthesis and magnetic properties study of the novel layered triangular compounds RE_3Ru_4Al_<12> (RE=La-Nd)
  Ge Wanyin; Michioka Chishiro; Ohta Hiroto; Yoshimura Kazuyoshi
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 65(2) 527 - 527, 18 Aug. 2010
• 24pWH-14 NMR studies of the novel quasi two-dimensional superconducting Fe(Te-Se) system 1
  Michioka C.; Ohta H.; Matsui M.; Yang J.; Yoshimura K.; Fang M.
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 65(2) 572 - 572, 18 Aug. 2010
• 24pWH-15 ^<77>Se NMR Study of Quasi-two-dimensional Superconductor Fe(Te-Se)
  OHTA Hiroto; MICHIOKA Chishiro; MATSUI Mami; KAWA Masatomo; YANG Jinhu; YOSHIMURA Kazuyoshi; FANG Minghu
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 65(2) 572 - 572, 18 Aug. 2010
• 23aPS-63 Synthesis and property of PbO-type FeTe and surrounding compounds
  Matsui Mami; Yang Jin Hu; Ohta Hiroto; Michioka Chishiro; Yoshimura Kazuyoshi
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 65(2) 474 - 474, 18 Aug. 2010
• 23aPS-58 Synthesis and physical property of PbO-type FeSe
  Kawa M.; Yang J. H.; Ota H.; Michioka T.; Yoshimura K.
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 65(2) 473 - 473, 18 Aug. 2010
• 23aPS-67 Syntheses and physical properties of ThCr_2Si_2 type ternary compounds RFe_2T_2(R=rare-earth metal, alkali earth metal, T=Ge,Si)
  Kobayashi S.; Ohta H.; Michioka C.; Yoshimura K.
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 65(2) 475 - 475, 18 Aug. 2010
• 23aPS-62 Specific heat and electric resistivity of layered compounds LnCoAsO
  OHTA Hiroto; MICHIOKA Chishiro; YOSHIMURA Kazuyoshi
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 65(2) 474 - 474, 18 Aug. 2010
• 23aPS-66 Physical properties of CaFe_4As_3
  Osada Yoshiaki; Ohta Hiroto; Michioka Chishiro; Yoshimura Kazuyoshi
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 65(2) 475 - 475, 18 Aug. 2010
• 20aPS-33 Synthesis and magnetic properties of Fe_3GeTe_2
  Chen B.; Yang J. H.; Ohta H.; Michioka C.; Yoshimura K.
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 65(1) 456 - 456, 01 Mar. 2010
• 23aGH-5 NMR studies of the novel quasi two-dimensional superconducting Fe(Te-Se) system 1
  Michioka C.; Ohta H.; Matsui M.; Yang J.; Yoshimura K.; Fang M.
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 65(1) 674 - 674, 01 Mar. 2010
• 23aGH-6 NMR studies of the novel quasi two-dimensional superconducting Fe(Te-Se) system 2
  Ohta H.; Michioka C.; Matsui M.; Yang J.; Yoshimura K.; Fang M.
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 65(1) 675 - 675, 01 Mar. 2010
• 20pPSB-34 Synthesis and property of FeTe and surrounding compounds
  Matsui Mami; Yang Jinhu; Ohta Hiroto; Michioka Chishiro; Yoshimura Kazuyoshi
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 65(1) 585 - 585, 01 Mar. 2010
• 20pPSB-21 Synthesis and physical property of PbO-type FeSe
  Kawa M.; Yang J. H.; Ota H.; Michioka T.; Yoshimura K.
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 65(1) 582 - 582, 01 Mar. 2010
• 21aGH-2 Magnetic and Superconducting Properties of Single Crystals of Fe(Te-Se) System
  Yang Jinhu; Matsui Mami; Kawa Masatomo; Ohta Hiroto; Michioka Chichiro; Yoshimura Kazuyoshi; Dong Chiheng; Wang Hangdong; Yuan Huiqiu; Fang Minghu
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 65(1) 599 - 599, 01 Mar. 2010
• 27pRH-13 Microscopic studies of layered compounds LaCoAsO
  Ohta Hiroto; Michioka Chishiro; Yoshimura Kazuyoshi
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 64(2) 547 - 547, 18 Aug. 2009
• 25pPSA-40 NMR Study and Spin Fluctuations in A_3B-type Itinertant-electron Magnets
  Chen B.; Ohta H.; Michioka C.; Yoshimura K.
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 64(2) 347 - 347, 18 Aug. 2009
• 26aPS-39 NMR study of the itinerant Pyrochlore oxide Pb_2Re_2O_<7-δ> and substitution effect of itinerant Pyrochlore oxides
  Michioka C.; Kataoka Y.; Ohta H.; Yoshimura K.
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 64(2) 487 - 487, 18 Aug. 2009
• 26aPS-64 LiCoO_2を出発物質とする含水コバルト酸化物の研究2(領域8ポスターセッション(低温(Cu,Ru,Mn,Co酸化物など,磁束量子系,鉄系超伝導体)),領域8,強相関系:高温超伝導,強相関f電子系など)
  森下 翔; 太田 寛人; 道岡 千城; 吉村 一良
  日本物理学会講演概要集, 一般社団法人日本物理学会, 64(2) 492 - 492, 18 Aug. 2009
• 26aPS-121 Synthesis and physical property of PbO-type FeSe
  Kawa M.; Yang J. H.; Ota H.; Michioka T.; Yoshimura K.
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 64(2) 504 - 504, 18 Aug. 2009
• 26aPS-126 Synthesis and property of FeTe and surrounding compounds
  Matsui Mami; Yang Jin Hu; Ohta Hiroto; Michioka Chishiro; Yoshimura Kazuyoshi
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 64(2) 505 - 505, 18 Aug. 2009
• 26aPS-133 Magnetic properties of layered compounds LnCoAsO
  Ohta Hiroto; Michioka Chishiro; Matsuo Akira; Kindo Koichi; Yoshimura Kazuyoshi
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 64(2) 507 - 507, 18 Aug. 2009
• 26aPS-125 Synthesis and Physical Properties of (Fe, T)(Te, X)(T=Co, Ni; X=S, Se)
  Yang Jin Hu; Matsui Mami; Ohta Hiroto; Michioka Chishiro; Yoshimura Kazuyoshi
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 64(2) 505 - 505, 18 Aug. 2009
• 28aTL-2 層状化合物LaCoAsOの磁気的性質(28aTL Co酸化物,領域8(強相関系:高温超伝導,強相関f電子系など))
  太田 寛人; 道岡 千城; 吉村 一良
  日本物理学会講演概要集, 一般社団法人日本物理学会, 64(1) 590 - 590, 03 Mar. 2009
• 28aTL-4 LiCoO_2を出発物質とする含水コバルト酸化物の研究(28aTL Co酸化物,領域8(強相関系:高温超伝導,強相関f電子系など))
  森下 翔; 太田 寛人; 吉村 一良
  日本物理学会講演概要集, 一般社団法人日本物理学会, 64(1) 591 - 591, 03 Mar. 2009
• 27aPS-95 Magnetic Properties of Ni_3AlC_x
  Chen B.; Ohta H.; Michioka C.; Itoh Y.; Yoshimura K.
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 64(1) 435 - 435, 03 Mar. 2009
• 21aQE-2 ^<59>Co NQR Study of superconducting Na_xCoO_2・yH_2O
  OHTA Hiroto; MICHIOKA Chishiro; ITOH Yutaka; YOSHIMURA Kazuyoshi
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 63(2) 484 - 484, 25 Aug. 2008
• 24pYB-5 μ^+SR study of bilayer hydrated Na_xCoO_2・yH_2
  Ohta Hiroto; Michioka Chishiro; Itoh Yutaka; Yoshimura Kazuyoshi; Ikedo Yutaka; Sugiyama Jun; Russo Peter L.; Ansaldo Eduardo J.; Chow Kim; Brewer Jess H.
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 63(1) 612 - 612, 29 Feb. 2008
• 24pYB-4 Co-NQR measurements on Single Crystals of Superconducting Hydrated Cobaltate Na_x(H_3O)_zCoO_2・yH_2O
  Sugawara H; Ihara Y; Ishida K; Ohta H; Yoshimura K; Takada K; Sasaki T; Sakurai Y; Muromachi E
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 63(1) 612 - 612, 29 Feb. 2008
• 23pWH-3 ^<23>Na NMR and ^<59>Co NQR studies of layered compound Na_xCoO_2・yH_2O
  Russo Peter L.; Chow Kim H.; Brewer Jess H.
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 62(2) 635 - 635, 21 Aug. 2007
• 21aWG-1 The study of duration effect and microscopic measurements of superconductor Na_xCoO_2・yH_2O
  Ohta Hiroto; Michioka Chishiro; Itoh Yutaka; Yoshimura Kazuyoshi
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 62(1) 639 - 639, 28 Feb. 2007
• 25pZL-6 ^<23>Na, ^1H and ^2D NMR study of layered compound Na_xCoO_2・yH_2O
  Ohta H.; Michioka C.; Itoh Y.; Yoshimura K.
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 61(2) 504 - 504, 18 Aug. 2006
• 30aUF-2 ^<23> Na NMR study of Na_xCoO_2・yH2_O
  Ohta H.; Michioka C.; Itoh Y.; Yoshimura K.
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 61(1) 649 - 649, 04 Mar. 2006
• 21aXD-7 Duration dependence and ^<23>Na NMR study of Na_xCoO_2・yH_2O
  Ohta Hiroto; Michioka Chishiro; Itoh Yutaka; Yoshimura Kazuyoshi
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 60(2) 467 - 467, 19 Aug. 2005
• 25pWF-3 Multi-NMR Studies of Triangular-Lattice Superconductor Na_xCoO_2・yH_2O
  Michioka Chishiro; Muromachi Eiji; Takada Kazunori; Sasaki Takayoshi; Ohta Hiroto; Itoh Yutaka; Waki Takeshi; Yoshimura Kazuyoshi; Kato Masaki; Ishida Kenji; Ihara Nobuhiko; Sakurai Hiroya
  Meeting Abstracts of the Physical Society of Japan, The Physical Society of Japan, 60(0) 558 - 558, 2005
• 25pWF-4 NMR studies of Na_xCoO_2・yH_2O superconductors and the related compounds
  Ohta Hiroto; Muromachi Eiji; Takada Kazunori; Sasaki Takayoshi; Michioka Chishiro; Itoh Yutaka; Waki Takeshi; Yoshimura Kazuyoshi; Kato Masaki; Ishida Kenji; Ihara Nobuhiko; Sakurai Yuya
  Meeting Abstracts of the Physical Society of Japan, The Physical Society of Japan, 60(0) 558 - 558, 2005
• 14pPSB-7 Low Temperature Specific Heat of Yb_0.8Y_0.2InCu_4 under Pressure
  Nambu T; Tsuchiya T.; Mitsuda A; Isikawa Y; Kuwai T; Goto T; Ohta H; Zhang W; Yoshimura K
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 59(2) 564 - 564, 25 Aug. 2004
• 14pPSB-13 The crystal structure and physical properties of new quarternary compound Yb-M-Ga-Ge(M=N_1, Co)
  OHTA H; MICHIOKA C; YOSHIMURA K
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 59(2) 566 - 566, 25 Aug. 2004
• 14aRC-2 Yb_<1-x>Y_xInCu_4(x=0, 01) の強磁場 X 線回折(価数揺動, 領域 8)
  松田 康弘; 稲見 俊哉; 大和田 謙二; 村田 悠人; 野尻 浩之; 村上 洋一; 張 維; 太田 寛人; 吉村 一良
  日本物理学会講演概要集, 一般社団法人日本物理学会, 59(2) 520 - 520, 25 Aug. 2004
• 14aRC-3 Magnetization measurenient of Yb_09Y_01InCu_4 under high pressure in the extremely low temperature ranges
  Mitsuda A; Yamauchi K; Isikawa Y; Yamada M; Goto T; Kolomiyets O; Ohta H; Zhang W; Yoshimura K
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 59(2) 520 - 520, 25 Aug. 2004
• 27pXD-3 Physical Properties of Yb_<1-x>R_xInCu_4(R=Y,La,Ce)
  Ohta H.; Zhang W.; Yoshimura K.; Mushmikov N. V.; Goto T.; Mitsuda A.
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 59(1) 531 - 531, 03 Mar. 2004
• Physical properties of Yb_<1-x>R_xInCu_4 (R=Y, La, Ce) single crystals (I)
  Ohta Hiroto; Zhang Wei; Yoshimura Kazuyoshi; Goto Tsuneaki; Mistuda Akihiro
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 58(2) 486 - 486, 15 Aug. 2003
• Magnetization measurement under high-pressure on Yb_<0.9>Y_<0.1>InCu_4
  Nihonmatsu H.; Mitsuda A.; Isikawa Y.; Yamada M.; Kolomiyets O.; Goto T.; Zhang W.; Ohta H.; Yoshimura K.
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 58(2) 464 - 464, 15 Aug. 2003
• Cu-NMR, NQR studies In heavy Fermion compound YbCu_5
  Ihara Y; Ishida K; Zhang W; Tsujii N; Ohta H; Yoshimura K
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 58(2) 563 - 563, 15 Aug. 2003
• H-T Phase Diagram of Valence Transition in the Intermetallic compounds of Yb_<1-x>Y_xInCu_4
  Zhang Wei; Onda Daisuke; Ohta Hiroto; Yoshimura Kazuyoshi; Mushnikov N. V.; Goto Tsuneaki; Mistuda Akihiro
  Meeting abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 58(1) 545 - 545, 06 Mar. 2003

Presentations

• 23Na, 1H and 2D NMR study of layered compound Na2CoO2・yH2O
  H. Ohta; C. Michioka; Y. Itoh; K. Yoshimura
  The physical society of Japan, 2006 Autumn Meeting, 25 Sep. 2006, Oral presentation
• 23Na NMR study of NaxCoO2・yH2O
  H. Ohta; C. Michioka; Y. Itoh; K. Yoshimura
  The physical society of Japan, 2006 Annual (61st) Meeting, 30 Mar. 2006, Oral presentation
• Duration dependence and 23Na NMR study of NaxCoO2・yH2O
  H. Ohta; C. Michioka; Y. Itoh; K. Yoshimura
  The physical society of Japan, 2005 Autumn Meeting, 21 Sep. 2005, Oral presentation
• NMR studies of NaxCoO2・yH2O superconductors and the related compounds
  H, Ohta; C. Michioka; Y. Itoh; T. Waki; K. Yoshimura; M. Katoh; K. Ishida; Y. Ihara; H. Sakurai; E. Muromachi; K. Takada; T. Sasaki
  The physical society of Japan, 2005 Annual (60th) Meeting, 25 Mar. 2005, Oral presentation
• Physical properties of Yb1-xRxInCu4 (R = Y, La, Ce)
  H. Ohta; W. Zhang; K. Yoshimura; N. V. Mushnikov; T. Goto; A. Mitsuda
  The physical society of Japan, 2004 Annual (59th) Meeting, 27 Mar. 2004, Oral presentation

Research Projects

• Study on new functional enhancement methods of itinerant ferromagnets in transition-metal pnictides
  太田 寛人
  ①サブナノシート磁石の研究では、層状化合物であるEuCo2P2のNi置換系において観測されていた強磁性相と反強磁性相への転移をEuメスバウアー分光等を用いて詳しく調べ、強磁性-反強磁性転移がEuの価数転移で引き起こされていることを指摘した。引き続き、Euの4f磁気モーメントと（反）強磁性秩序状態にあるCo/Niの3d電子との相互作用について詳しく調べていく。 また、層状構造の物質として六方晶系のReMnCuP2の合成に成功し、電気伝導性を示すことおよびMnの3d電子が局在磁気モーメント的に振る舞うことを明らかにした。 ②局在磁気モーメントの誘起の研究では、前年度にFeの局在磁気モーメントを観測したY2Fe3Ni9P7についてFeとNiのサイト占有状況をFeメスバウアー分光を用いて調べ、他の元素の組み合わせよりもサイト間の置き換わりが多く発生していることを明らかにした。低温で観測されたスピングラスはこのサイト間のランダム置換に起因することを指摘した。 Zr2Fe12P7型構造のリン化物の関連物質であるいくつかの物質の合成を試み、REMnCu4P3においてMnが局在磁気モーメントを有することを明らかにした。MnはY2Fe3Ni9P7におけるFeと同様のリンの５配位サイトを占有しており、これら遷移金属リン化物においてリンの４配位サイトよりも５配位サイトの方が占有する遷移金属のd電子が局在しやすい傾向にあることをしめしている。このことは第一原理計算でもサイト間の電子密度の分布の違いから理解でき、５配位サイトでは周りのリンとの化学結合が弱いことがd電子の局在性の高さの原因である。 新たにより基本的な構造であるFe2PやCo2P型構造の遷移金属リン化物について研究を開始し、新しい固溶系の合成に成功した。, Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, 2020/04 -2023/03, Grant-in-Aid for Scientific Research (C)
• Emergent Research for Novel Itinerant-Electron Properties in Transition-Metal Compounds
  吉村 一良; 那波 和宏; 小林 慎太郎; 太田 寛人; 道岡 千城
  新たな量子物性を生み出す新物質の創成は，固体物性物理化学の基礎・応用研究の両分野の発展に大きな貢献をもたらし，この研究分野のブレイクスルーへと繋がるものである．本研究では，海外と日本の研究者が協力し，フラストレート効果と低次元性，さらに構造相転移との組み合わせによって，興味ある遍歴電子物性を示す新規の遍歴電子遷移金属物質群を探索・合成し，その新規遍歴電子物性についてのマクロ及びミクロの両面から明らかにし，その実験結果を解析しフィードバックして，固体物性化学的な基盤を確立することを目的としている． これまでの研究で中国・香港中文大学のSwee K. Goh博士と中国・浙江大学のMinghu Fang（方 明虎）教授と強結合超伝導体A3T4Sn13系（A=Ca, Sr, La; T=Co, Rh, Ir）について，超伝導の発現機構について明らかにする研究を行った．その結果，超伝導転移温度と光学フォノンのソフトニングに強い相関の詳細を明らかにしている．2021年度は，これらの物質のバンド構造をDFT計算から明らかにし，トポロジカル電子系に特徴的な振舞が現れる，磁場中電気抵抗を用いた詳細な相図の研究を行った．またウイーン工科大学のMichor博士との共同研究で遍歴電子系RCo9(R=希土類金属)，1-2-2系の遍歴電子強磁性系・エキゾチック超伝導系であるB(Fe-Co)2Se2 (B=K, Tl, Rb, Cs, Ca, Sr, Ba, La)系について新たな物質系を開拓し，単結晶育成と物性解明を行った．また，北京大のWei Han教授グループとマグノンBEC物質についてスピン・ゼーベック効果の研究も新たに行った．, Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, 2018/10 -2023/03, Fund for the Promotion of Joint International Research (Fostering Joint International Research (B)), Kyoto University
• Study on functional materials and ways of their functional enhancement from viewpoint of sub-nanosheet magnets
  Ohta Hiroto
  In this project, I have focused on the magnetic layers with a thickness as large as a few atoms in the layered itinerant magnets, and for this "sub-nano sheet magnet" I have investigated its common nature and physical properties caused by interaction between this sheet and intermediate layer blocks. As results, in a layered antiferromagnetic compound EuCo2P2, partial Ni-substitution for Co is found to induce ferromagnetic ordering instead of the antiferromagnetic one, and also in this ferromagnetic phase new antiferromagnetic ordering was found, which is similar antiferromagnetic phase seen in LnCoPnO. Thus, Ni-substituted EuCo2P2 is locating near the three phase boundaries of Eu valences, tetragonal structural, and magnetic phases, so this system can be controlled by several factors such as magnetic filed and pressure. Also, this system is expected to show novel phases because of such triple degrees of freedom., Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, 2017/04 -2020/03, Grant-in-Aid for Scientific Research (C)
• Study of Undergraduate Laboratory Subjects without Manuals
  Matsuzaki Seiji
  Nowadays, educational effects of active learning are said to be superior than those of passive methods. Is active learning also effective in undergraduate laboratory in higher education? Our group introduced some subjects into undergraduate laboratory courses without detailed manuals. We measured their educational effects from some questionnaires, systematic evaluation of the procedure of students’ thinkings, and results of students’ presentations. In conclusion, their effects were superior than cooking-recipe type experiments in understanding physical concepts, and they made students more motivated., Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, 2014/04 -2018/03, Grant-in-Aid for Scientific Research (C), Tokyo University of Agriculture and Technology
• Study on mechanism of anomalous behavior of localized magnetic moments in itinerant electronic ferromagnets
  OHTA Hiroto; KATORI Hiroko; WATANABE Yusuke; SUZUKI Atsushi; KATO Yusuke
  We found an anomalous behavior of localized magnetic moments in itinerant electronic ferromagnets, and have tried to clarify the mechanism of it. As results, we found that localized magnetic moments couple with internal field from ferromagnetic sublattice, leading to the anomalous temperature and magnetic field dependences of them. Such a coupling can be seen as the coupling of ferromagnetic moments with localized magnetic moments, and this viewpoint indicates a possibility to control ferromagnetic moments through controlling localized magnetic moments which couple with ferromagnetic moments. We found that the ferromagnetic-antiferromagnetic transition observed in layered ferromagnetic compounds can be understood by this mechanism., Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, 2015/04 -2017/03, Grant-in-Aid for Young Scientists (B), Tokyo University of Agriculture and Technology
• Research of new functional compounds in layered structure with two-dimensional electronic systems
  OHTA Hiroto
  Among layered compounds with cobalt pnictogen layers, LnCoAsO (Ln: lanthanoids) shows itinerant electronic ferromagnetism. Sr2ScO3CoAs, which has 2 times larger intra-layer distance, also shows ferromagnetism, showing that itinerant electronic ferromagnetism realizes in layered compounds despite of the intra-layer distance. Ferromagnetic-antiferromagnetic transition occurs in LnCoAsO, but its mechanism has been still unresolved. In my study, Sr2(Sc,V)O3CoAs has been found to show ferromagnetic-antiferromagnetic transition. This fact shows that such transition occurs in a condition that localized magnetic moments are sandwiched by itinerant electronic ferromagnetic layers., Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, 2012/04 -2014/03, Grant-in-Aid for Young Scientists (B), Tokyo University of Agriculture and Technology
• Syntheses of New 2-Dimensional Itinerant-Electron Compounds and Search for Novel Physical Properties
  YOSHIMURA Kazuyoshi; MICHIOKA Chishiro
  The research on 2-dimensional itinerant-electron systems has been conducted in order to investigate and to establish novel 2-dimensional itinerant-electron systems by controlling the electronic states of transition-metal elements. As a result, we newly found the itinerant-electron metamagnetic transitions around 60 T in the high-fieldmagnetization process of SrCo2P2. By substituting Ca for Sr, the system was found to approach the QCP of the 2D itinerant ferromagnetism. In the 2-dimensional superconductingsystem Fe(Te-Se), furthermore, physical properties were investigated by utilizing 125Te NMR. Consequently, the mechanism of this superconductivity was found to be due to the antiferromagnetic spin-fluctuation., Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, 2010 -2012, Grant-in-Aid for Scientific Research (B), Kyoto University
• 新規層状構造化合物の創製とその遍歴電子物性
  太田 寛人
  年度途中における所属の変更があったため、コバルト酸化物に関する研究は研究環境の整備が間に合わず、実行まで至らなかった。そこでもう一方の研究目的であったコバルトニクタイドに研究を集中して行った。その結果、コバルト砒化物であるSrCo_2As_2およびSr_2ScO_3CoAsの合成に成功した。これらの物質のCoAs面間距離はこれまで研究して来たLaCoAsOに比べてSrCo_2As_2では短く、Sr_2ScO_3CoAsでは約2倍と長い。一般的にハイゼンベルグ・モデルにおいて磁気秩序が実現するには三次元的な相互作用が働く必要があり、純粋な二次元では磁気秩序が実現しない。今回研究した層状化合物では積層面内で比較的強い相互作用が働く一方で、面間の相互作用は面間距離に依存し、近いほど磁気秩序に有利であると考えられる。しかし、磁化測定の結果、SrCO_2As_2では磁気秩序が低温まで見られず、磁気的なパラメータからも強磁性に近い金属であることが分かった。一方で、Sr_2ScO_3CoAsではLaCoAsOとほぼ同じ温度(約60K)において強磁性転移が観測された。今回の結果から二つの点が推測される。一つは、Sr_2ScO_3CoAsとLaCoAsOが良く似た強磁性秩序を示すことから、面間距離はLaCoAsOで十分はなれており、面間距離とは無関係に強磁性秩序のパラメータが決まっている。もう一つは、SrCo_2As_2は他の二つの物質とは電子状態が異なっており、単純に比較できない点である。前者に関しては、遍歴電子系においても磁気秩序に次元性が重要であるはずなので、何らかの方法で非二次元性を得ていると考えられる。そのメカニズムの解明が重要であるが、今年度の研究では解明に至らなかった。後者に関しては、SrCo_2As_2を含む122系化合物は先に揚げた他の二つの物質と比べて特異な電子状態にある可能性がある。関連物質であるSrCo_2P_2において最近、二段階の遍歴電子メタ磁性転移が観測されており、特異な電子状態の現れた例であると考えられる。この点に関しても本研究内で解明には至らなかったが、先の非二次元性の問題も含めて遍歴電子強磁性の研究において解決すべき課題である。, 日本学術振興会, 科学研究費助成事業, 2011 -2011, 特別研究員奨励費, 東京農工大学
• 三角格子超伝導体二酸化コバルトナトリウム水和物のトポタキシー
  太田 寛人
  層状構造を有する水二層Na_xCoO_2・yH_2Oを合成し、組成分析を行った。具体的にはNaの組成x、水の組成y、またNaサイトを一部占有していると言われるH_3O^+イオンの組成である。TG-DTAによる熱重量分析を行い、試料の重量に占める水とオキソニウムイオンの重さを見積もった。その後、学外の高周波誘導プラズマ分光装置を用いて試料の残りの部分のNaとCoO_2の比率を測定した。この時、酸素欠損はないと仮定した。其の結果、経時変化する性質を利用して合成した電子相図上の様々な状態の試料の組成に系統的な変化は見られなかった。一方で、室温における粉末X線回折測定から見積もっか格子定数aおよびcを相図と対応させると、格子定数aはほぼ一定であったのに対し、cは系統的な変化を示した。すなわち、電子相図の横軸に対応する^<59>Co核四重極共鳴周波数ν_Qに対して、格子定数cはともに減少することが分かった。以上の結果は、次の二通りに解釈できる。まず一つ目は、経時変化にともなう試料中の組成の変化はなく、電子状態の変化はCoO_2面間の配置の変化に依るものとする解釈である。また、もう一つは組成の変化が起きたが、同じ試料の組成の経時変化を迫いかけたため、変化が観測出来なかったという解釈である。組成の変化が起きる場合、当然粒子の表面からイオン等の交換が起きると考えられる。この場合、交換したイオンは粒子の表面に留まると考えられるので、ICP等の化学的な分析ではイオンが粒子の内部にあるとして見積もれてしまったと考えられる。この結果は水二層Na_xCoO_2・yH_2Oの電子状態を議論するにあたって、安易に見積もった組成と物性を結びつけることの危険性を表している。, 日本学術振興会, 科学研究費助成事業, 2007 -2008, 特別研究員奨励費, 京都大学