Precise study on the optical and dielectric response of the stoichiometric iron based electronic ferroelectrics

• Project/Area Number: 19H01827
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 13020:Semiconductors, optical properties of condensed matter and atomic physics-related
• Research Institution: Okayama University
• Principal Investigator: IKEDA NAOSHI 岡山大学, 自然科学学域, 教授 (00222894)
• Co-Investigator(Kenkyū-buntansha): 沖本 洋一 東京工業大学, 理学院, 准教授 (50356705)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Project Status: Completed (Fiscal Year 2021)
• Budget Amount: ¥17,420,000 (Direct Cost: ¥13,400,000、Indirect Cost: ¥4,020,000); Fiscal Year 2021: ¥5,460,000 (Direct Cost: ¥4,200,000、Indirect Cost: ¥1,260,000); Fiscal Year 2020: ¥5,460,000 (Direct Cost: ¥4,200,000、Indirect Cost: ¥1,260,000); Fiscal Year 2019: ¥6,500,000 (Direct Cost: ¥5,000,000、Indirect Cost: ¥1,500,000)
• Keywords: 電子強誘電体 / RFe2O4 / LuFe2O4 / YbFe2O4 / YFe2O4 / シフト電流 / 電気分極 / 電子相関 / 電子強誘電性 / electronic ferroelectric / ferroelectrics / 電子誘電体 / 電子強誘電相 / 電子型強誘電体 / 強誘電体 / 電子誘電性 / マルチフェロイック物質 / 非線形光応答 / ポンププローブ測定 / フラストレーション

Outline of Research at the Start

強誘電体材料は現代の電子回路技術全てに必須であり、その強誘電体研究と工業生産において日本は世界的リーダーにある。近未来の電子回路技術では、超高周波回路や超小型誘電体材料が必要であり、それに対応する強誘電体の開発が求められている。我々が世界に先駆けて発見した電子強誘電体は、今までの強誘電体と異なりイオン変位ではなく電子の偏った分布から強誘電性が現れる。このため超高速動作や、省エネルギー動作が期待されている。本研究は、精密結晶合成技術と超高速光応答測定技術を駆使し、電子型強誘電体が持つ新奇で高速な誘電特性の解明・開拓を行う。我々は当概念の提唱者であり、世界に先んじて電子強誘電体の基礎を確立する。

Outline of Final Research Achievements

This research has demonstrated for the first time in the world that an electron ferroelectric material exists stably at room temperature. Furthermore, we were able to show that this electronic phase also exists in thin film samples. The electric polarization consisting of only the electron distribution in the electron ferroelectric material is expected to respond significantly faster than that in the displacement-type ferroelectric material, which has been known until now.
A new dielectric relaxation analysis method using single crystals was developed for the electric polarization of electronic ferroelectrics, which inevitably involves the electric resistivity. As a result, we were able to experimentally show for the first time that in fine charge-ordered domains, charge-ordered nanoregions with larger capacitance have higher electrical resistance.

Academic Significance and Societal Importance of the Research Achievements

電子型強誘電体は、電子応答だけが誘電応答を示すため、既存の強誘電体に比べ、3桁程度早く、また低エネルギーで応答することが可能であると期待されている。本研究によるその実在の確認は、現状に比べ情報密度や省エネルギー性が３桁向上した、将来の超高速情報通信社会形成のために、重要な基盤材料を提示できたと考えられる。
この材料が産業利用に整合するためには、多くの精査が必要であろうが、本研究はその第一歩となった。

Research Products

• [Int'l Joint Research] Oak Ridge National Laboratory(米国)
• [Journal Article] Direct evidence of electronic ferroelectricity in YbFe_2_O_4_ using neutron diffraction and nonlinear spectroscopy (2021)
  • Author(s): K. Fujiwara, Y. Fukada, Y. Okuda, R. Seimiya, N. Ikeda, K. Yokoyama, H. Yu, S. Koshihara, Y. Okimoto
  • Journal Title: Scientific Reports Volume: 11 Issue: 1 Pages: 4277-4277
  • DOI: 10.1038/s41598-021-83655-6
  • Peer Reviewed / Open Access
• [Journal Article] Observation of Magnetoelectric Effect of Charge-Ordered Ferroelectric LuFe₂O₄ by Inverse Capacitance Analysis (2021)
  • Author(s): Fukada Yukimasa、Ikeda Naoshi
  • Journal Title: Journal of the Physical Society of Japan Volume: 90 Issue: 11 Pages: 113705-113705
  • DOI: 10.7566/jpsj.90.113705
  • NAID: 210000159395
  • Peer Reviewed
• [Journal Article] Analysis of Glass Behavior of Lu2Fe3O7 with Distributed Equivalent Circuit Model (2021)
  • Author(s): Fukada Yukimasa、Fukuyama Ryota、Fujiwara Kosuke、Yoshii Kenji、Shigematsu Kei、Azuma Masaki、Ikeda Naoshi
  • Journal Title: Journal of the Physical Society of Japan Volume: 90 Issue: 2 Pages: 024710-024710
  • DOI: 10.7566/jpsj.90.024710
  • NAID: 40022485018
  • Peer Reviewed
• [Journal Article] Crystallographical and morphological changes in charge-ordering transition of RFe₂O₄ (R: Y, Lu) investigated by transmission electron microscopy (2021)
  • Author(s): Horibe Y.、Mori S.、Ikeda N.、Yoshii K.、Maeno H.、Murakami Y.
  • Journal Title: Ferroelectrics Volume: 584 Issue: 1 Pages: 20-30
  • DOI: 10.1080/00150193.2021.1984762
  • Peer Reviewed
• [Journal Article] Single domain growth and charge ordering of epitaxial YbFe₂O₄ films (2021)
  • Author(s): Sakagami Takumi、Ota Reika、Kano Jun、Ikeda Naoshi、Fujii Tatsuo
  • Journal Title: CrystEngComm Volume: 23 Issue: 35 Pages: 6163-6170
  • DOI: 10.1039/d1ce00834j
  • Peer Reviewed / Open Access
• [Journal Article] Light reflectance and photoelectron yield spectroscopy enable acceptor level measurement in p-type Ba1-xTiO3 semiconductor (2021)
  • Author(s): Fujii Saya、Kano Jun、Oshime Norihiro、Higuchi Tohru、Nishina Yuta、Fujii Tatsuo、Ikeda Naoshi、Ota Hiromi
  • Journal Title: Journal of Applied Physics Volume: 129 Issue: 8 Pages: 084105-084105
  • DOI: 10.1063/5.0033761
  • Peer Reviewed
• [Journal Article] High valence states of Pd supported on ferroelectric BaTiO₃ driven by electric polarization (2021)
  • Author(s): Yoshida Tasuku、Kano Jun、Mizumaki Masaichiro、Tamenori Yusuke、Nitta Kiyofumi、Kato Kazuo、Hinokuma Satoshi、Oshime Norihiro、Hirose Satoshi、Mikami Hitoshi、Ikeda Naoshi、Fujii Tatsuo、Nishina Yuta、Okubo Tomoko
  • Journal Title: Applied Physics Letters Volume: 119 Issue: 9 Pages: 092904-092904
  • DOI: 10.1063/5.0066289
  • Peer Reviewed
• [Journal Article] Picosecond dynamics in layered cobalt perovskites studied by time-resolved Raman spectroscopy (2021)
  • Author(s): Fukaya Ryo、Yamaya Nao、Ishikawa Tadahiko、Koshihara Shin-ya、Okimoto Yoichi、Onda Ken、Isayama Akira、Sasagawa Takao、Horigane Kazumasa
  • Journal Title: Comptes Rendus. Physique Volume: 22 Issue: S2 Pages: 1-8
  • DOI: 10.5802/crphys.35
  • Peer Reviewed / Open Access
• [Journal Article] Polarization- and Strain-Mediated Control of Negative Thermal Expansion and Ferroelasticity in BiInO3-BiZn1/2Ti1/2O3 (2021)
  • Author(s): Nishikubo Takumi、Ogata Takahiro、Venkataraman Lalitha Kodumudi、Isaia Daniel、Pan Zhao、Sakai Yuki、Hu Lei、Kawaguchi Shogo、Machida Akihiko、Watanuki Tetsu、Yu Hongwu、Okimoto Yoichi、Koshihara Shin-ya、Mori Shigeo、Rudel Jorgen、Azuma Masaki
  • Journal Title: Chemistry of Materials Volume: 33 Issue: 4 Pages: 1498-1505
  • DOI: 10.1021/acs.chemmater.0c04049
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Skewed electronic band structure induced by electric polarization in ferroelectric BaTiO3 (2020)
  • Author(s): Oshime Norihiro、Kano Jun、Ikenaga Eiji、Yasui Shintaro、Hamasaki Yosuke、Yasuhara Sou、Hinokuma Satoshi、Ikeda Naoshi、Janolin Pierre-Eymeric、Kiat Jean-Michel、Itoh Mitsuru、Yokoya Takayoshi、Fujii Tatsuo、Yasui Akira、Osawa Hitoshi
  • Journal Title: Scientific Reports Volume: 10 Issue: 1 Pages: 10702-10702
  • DOI: 10.1038/s41598-020-67651-w
  • NAID: 120006872416
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Ultrafast Nonlinear Spectroscopy in (111) Oriented Bismuth Ferrite Oxide (2020)
  • Author(s): Yu Hongwu、Takubo Kou、Ishikawa Tadahiko、Koshihara Shin-ya、Hada Masaki、Asaka Toru、Ozawa Keita、Shigematsu Kei、Azuma Masaki、Okimoto Yoichi
  • Journal Title: Journal of the Physical Society of Japan Volume: 89 Issue: 6 Pages: 063401-063401
  • DOI: 10.7566/jpsj.89.063401
  • NAID: 40022254109
  • Peer Reviewed
• [Journal Article] Enhanced Spontaneous Polarization by V4+ Substitution in a Lead-Free Perovskite CaMnTi2O6 (2020)
  • Author(s): Fukuda Masayuki、Nishikubo Takumi、Pan Zhao、Sakai Yuki、Zhang Mao-Hua、Kawaguchi Shogo、Yu Hongwu、Okimoto Yoichi、Koshihara Shin-ya、Itoh Mitsuru、Rudel Jorgen、Azuma Masaki
  • Journal Title: Inorganic Chemistry Volume: 59 Issue: 16 Pages: 11749-11756
  • DOI: 10.1021/acs.inorgchem.0c01697
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Stabilization of Spin and Charge Ordering in Stoichiometric YbFe2O4 (2019)
  • Author(s): Fujiwara Kosuke、Karasudani Tomoyuki、Kakurai Kazuhisa、Lee Wai Tung、Rule Kirrily C.、Studer Andrew J.、Ikeda Naoshi
  • Journal Title: Journal of the Physical Society of Japan Volume: 88 Issue: 4 Pages: 044701-044701
  • DOI: 10.7566/jpsj.88.044701
  • Peer Reviewed / Int'l Joint Research
• [Presentation] 鉄欠損抑制によるRFe2O4 (R=Yb,Lu)の3次元電荷秩序温度の向上 (2022)
  • Author(s): 藤原孝将, 深田幸正, 清宮僚人, 亀井朝日, 鈴木孝義, 池田直
  • Organizer: 日本物理学会 第76回年次大会,
• [Presentation] 第二次高調波発生から見たLuFe2O4 結晶の電子強誘電性 (2022)
  • Author(s): 于洪武, 森田敦也, 石川忠彦, 腰原伸也, 深田幸正, 藤原孝将, 池田直, 岸田晶穂, 伊藤毅, 岩井伸一郎, 沖本洋一
  • Organizer: 日本物理学会 第76回年次大会,
• [Presentation] Electronic ferroelectric LuFe2O4 crystal Time-resolved SHG measurement (2021)
  • Author(s): 于洪武、田久保耕、石川忠彦、腰原伸也、深田正幸、西田銀一、池田直、藤原孝将、 大田伶佳、阪上拓巳、 藤井達生、 岸田晶穂、 伊藤弘毅、 岩井伸一郎、沖本洋一
  • Organizer: MRM2021
  • Int'l Joint Research
• [Presentation] Electronic Ferroelectricity from the Polar Charge Ordering of RFe2O4 (2021)
  • Author(s): Naoshi Ikeda, Kosuke Fujiwara, Hongwu Yu, Yukimasa Fukada, Tatsuo Fujii, Yoichi Okimoto
  • Organizer: MRM2021
  • Int'l Joint Research / Invited
• [Presentation] Short-Range Spin Ordering near Room Temperature in Stoichiometric LuFe2O4 (2021)
  • Author(s): Kosuke Fujiwara, Yukimasa Fukada, Ginichi Nishida, Yohei Okuda, Naoshi Ikeda, Kazuhisa Kakurai, Matthias Frontzek
  • Organizer: MRM2021
  • Int'l Joint Research
• [Presentation] Time-resolved Nonlinear Spectroscopy of the Electronic Ferroelectric iron oxide Lu Fe2O4 (2021)
  • Author(s): H. Yu, Y. Fukada, R. Kiyomiya, N. Ikeda, H. Itoh, S. Iwai, T. Ishikawa, S. Koshihara, and Y. Okimoto
  • Organizer: Photoinduced Phase Transitions and Cooperative Phenomena, 2021
  • Int'l Joint Research
• [Presentation] 電子強誘電体Lu Fe2O4結晶の時間分解SHG測定 (2021)
  • Author(s): 于洪武, 田久保耕, 石川忠彦, 腰原伸也, 藤原孝将, 深田幸正, 西田銀一, 池田直, 沖本洋一
  • Organizer: 日本物理学会 2021年秋季大会
• [Presentation] 化学当量的なYFe2O4の特異な電荷秩序相の発見 (2021)
  • Author(s): 藤原孝将, 清宮僚人, 深田幸正, 西田銀一, 亀井朝日, 鈴木孝義, 池田直
  • Organizer: 日本物理学会 2021年秋季大会
• [Presentation] 電子強誘電体YbFe2O4薄膜結晶の非線形光学測定 (2021)
  • Author(s): 于洪武, 田久保耕, 石川忠彦, 腰原伸也, 阪上拓巳, 大田怜佳, 藤井達生, 深田幸正, 藤原孝将, 池田直, 沖本洋一
  • Organizer: 日本物理学会 2021年秋季大会
• [Presentation] 緩和時間分布を考慮したLuFe2O4の磁場中逆容量解析 (2021)
  • Author(s): 深田幸正, 西田銀一, 藤原孝将, 狩野旬, 藤井達生, 池田直
  • Organizer: 日本物理学会 2021年秋季大会
• [Presentation] 鉄欠損抑制によるRFe2O4(R=Yb,Lu)の3次元電荷秩序温度の向上 (2021)
  • Author(s): 藤原孝将, 深田幸正, 清宮僚人, 亀井朝日, 鈴木孝義, 池田直
  • Organizer: 日本物理学会 第76回年次大会
• [Presentation] 第二次高調波発生から見たLuFe2O4結晶の電子強誘電性 (2021)
  • Author(s): 于洪武, 森田敦也, 石川忠彦, 腰原伸也, 深田幸正, 藤原孝将, 池田直, 岸田晶穂, 伊藤毅, 岩井伸一郎, 沖本洋一
  • Organizer: 日本物理学会 第76回年次大会
• [Presentation] Low-temperature phase transition of YFe2O4 single crystal of low iron deficiency (2020)
  • Author(s): R. Seimiya, K. Yu, Y. Okimoto, C. Kojima, Y. Fukada, K. Fujiwara, K. Kakurai, N. Ikeda
  • Organizer: 第30回 日本MRS年次大会
• [Presentation] Synthesis of Carbon Nano Walls from Solid Carbon with Gas Induced Plasma (2020)
  • Author(s): K. Sato, K. Nobuoka, Y. Aoyagi, Y. Fukada, M. Mori, Y. Nishina, J. Kano and N. Ikeda
  • Organizer: 第30回 日本MRS年次大会
• [Presentation] Ba欠損を導入した強誘電体BaTiO3のバンド構造 (2019)
  • Author(s): 藤井 沙耶，狩野 旬，那須 駿平，押目 典宏，藤井 達生，池田 直，太田 弘道
  • Organizer: 金研ワークショップ，強誘電体関連物質の機能発現に関する構造科学の新展開
• [Presentation] スパッタ法による YbFe2O4/Fe3O4 多層膜の作製 (2019)
  • Author(s): 大内崇弘、糸島 遼、中西 真、狩野 旬、藤井達生、池田 直
  • Organizer: ヤングセラミスト・ミーティングin 中四国
• [Presentation] YbFe2O4 のリチウムイオンドープ効果 (2019)
  • Author(s): 中井一樹、吉木幸宏、中西 真、狩野 旬、藤井達生、池田 直
  • Organizer: ヤングセラミスト・ミーティングin 中四国
• [Presentation] Successive Charge Ordering, Polar Charge Order and Electronic Ferroelectricity in Mixed Valences Iron Compound RFe2O4 (2019)
  • Author(s): Naoshi Ikeda
  • Organizer: Seminar of Universidad de Sonora
  • Int'l Joint Research / Invited
• [Presentation] Electric Properties of Doped Carbon Nanowalls with the Microwave PVD Method (2019)
  • Author(s): Y. Aoyagi, M. Yokoyama, K. Sato, M. Kobata, A. Tominaga, N. Shimode, A. Yoshigoe, S. Yamaguchi, M. Mori, Y. Nishina, J. Kano and N. Ikeda
  • Organizer: 29th annual meeting of Material Research Society of Japan
• [Presentation] Low-Temperature Phase Transition of Stoichiometric YFe2O4 Single Crystal (2019)
  • Author(s): R. Seimiya, K. Yu, Y. Okimoto, Y. Satake, Y. Fukada, K. Fujiwara, N. Ikeda
  • Organizer: 29th annual meeting of Material Research Society of Japan
• [Presentation] The analysis of physical property of Lu2Fe3O7 using impedance spectroscopy (2019)
  • Author(s): Y.Fukada, R. Fukuyama, K. Fujiwara, K. Yoshii and N. ikeda
  • Organizer: 29th annual meeting of Material Research Society of Japan
• [Presentation] スパッタ法による YbFe2O4/Fe3O4 多層膜の作製と磁気特性 (2019)
  • Author(s): 阪上 拓巳，西村 和泰，中西 真，狩野 旬，池田 直，藤井 達生
  • Organizer: 粉末冶金協会2019 年度秋季大会
• [Presentation] Valence Control of Charge and Orbital Frustrated System YbFe2O4 with Electrochemical Li+ intercalation. (2019)
  • Author(s): S. Murase, Y. Yoshikawa, K. Fujiwara, Y. Fukada, T. Teranishi, J. Kano. T. Fujii, Y. Inada, M. Katayama, K. Yoshii, T. Tsujii, D. Matsumura and N. Ikeda
  • Organizer: International conference on Strongly Correlated Electron Systems 2919
• [Presentation] Magnetic and Dielectric Properties of Lu2Fe3O7 (2019)
  • Author(s): Yukimasa FUKADA, Kenji YOSHII, Kosuke FUJIWARA, Naoaki HAYASHI, Tatsuo FUKUDA, Masaichiro MIZUMAKI, Kei SHIGEMATSU, Masaki AZUMA, Masayasu TAKEDA, and Naoshi IKEDA
  • Organizer: International conference on Strongly Correlated Electron Systems 2919
• [Presentation] インピーダンス分光法を用いたRFe2O4系の電気磁気相関現象の解析 (2019)
  • Author(s): 深田幸正, 吉井賢資, 藤原孝将, 福山諒太, 池田直
  • Organizer: 日本物理学会2019年秋季大会,
• [Presentation] 電子強誘電体LuFe2O4の非線形分光測定 (2019)
  • Author(s): 于洪武, 横山景祐, 石川忠彦, 腰原伸也, 沖本洋一, 深田幸正, 藤原孝将, 清宮僚人, 池田直
  • Organizer: 日本物理学会2019年秋季大会,
• [Presentation] Recent research progress on the electronic ferroelectric material RFe2O4 (2019)
  • Author(s): Naoshi IKEDA
  • Organizer: ISEAS-VII, workshop on frontiers in material sciences, Tamkang university
  • Int'l Joint Research / Invited
• [Remarks] 室温で結晶内の電子秩序が強誘電性を生み出すことを発見－超高速電子材料の実現へ－
  • URL: https://www.okayama-u.ac.jp/tp/release/release_id812.html?fbclid=IwAR1Eg1YVMaXXzHolZ8pUNiUaZNuPYDwXSOHiugJ_BGq1lpLSfqe8SeoibzI
• [Remarks] 室温で結晶内の電子秩序が強誘電性を生み出すことを発見
  • URL: https://www.titech.ac.jp/news/2021/049042
• [Remarks] 東工大ら，鉄セラミックス材料の強誘電性を発見
  • URL: https://optronics-media.com/news/20210222/72245/
• [Remarks] 室温で強誘電性を生み出す鉄セラミック材料を発見
  • URL: https://eetimes.itmedia.co.jp/ee/articles/2102/25/news040.html
• [Remarks] 室温で結晶内の電子秩序が強誘電性を生み出すことを発見 ～超高速電子材料の実現へ～
  • URL: https://www.nanonet.go.jp/ntj/topics_ntj/?mode=article&article_no=5503
• [Remarks] 室温で結晶内の電子秩序が強誘電性を生み出すことを発見－超高速電子材料の実現へ－
  • URL: https://www.okayama-u.ac.jp/tp/release/release_id812.html
• [Remarks] 室温で結晶内の電子秩序が強誘電性を生み出すことを発見
  • URL: https://www.titech.ac.jp/news/2021/049042.html