Optical control of electron-hole correlation in excitonic insulators

• Project/Area Number: 19H00659
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Medium-sized Section 13:Condensed matter physics and related fields
• Research Institution: Waseda University
• Principal Investigator: Mizokawa Takashi 早稲田大学, 理工学術院, 教授 (90251397)
• Co-Investigator(Kenkyū-buntansha): 岡村 英一 徳島大学, 大学院社会産業理工学研究部(理工学域), 教授 (00273756) ; 岡崎 浩三 東京大学, 物性研究所, 准教授 (40372528)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Project Status: Completed (Fiscal Year 2022)
• Budget Amount: ¥45,240,000 (Direct Cost: ¥34,800,000、Indirect Cost: ¥10,440,000); Fiscal Year 2022: ¥6,370,000 (Direct Cost: ¥4,900,000、Indirect Cost: ¥1,470,000); Fiscal Year 2021: ¥11,310,000 (Direct Cost: ¥8,700,000、Indirect Cost: ¥2,610,000); Fiscal Year 2020: ¥11,310,000 (Direct Cost: ¥8,700,000、Indirect Cost: ¥2,610,000); Fiscal Year 2019: ¥16,250,000 (Direct Cost: ¥12,500,000、Indirect Cost: ¥3,750,000)
• Keywords: エキシトニック絶縁体 / 時間分解光電子分光 / 圧力誘起相転移 / 光誘起相転移 / 電子正孔相関 / 擬ギャップ / 圧力下赤外分光 / 高圧下赤外分光

Outline of Research at the Start

エキシトニック絶縁体では、光励起されたキャリアーが電子正孔間引力を遮蔽することによる光誘起絶縁体金属転移など特異な光応答が期待されるが、その光応答は系統的に研究されていない状況である。特に、Ta2NiSe5は直接ギャップを持つエキシトニック絶縁体であり、圧力や光励起によって電子相を制御できる可能性が示唆されている。本研究課題では、Ta2NiSe5と関連物質についてフェムト秒時間分解光電子分光と圧力下の赤外分光測定を精密かつ系統的に行い、その電子・正孔ダイナミクスと光学フォノンとの結合の全容を解明する。さらに、光制御・圧力制御・原子層制御によってエキシトニック相に特有の新規な光機能開拓を目指す。

Outline of Final Research Achievements

We have revealed the electronic structure of the excitonic insulator phase and associated semimetal and semiconducting phases by means of time- or space-resolved angle-resolved photoemission spectroscopy. In particular, we have shown that the photoinduced semimetal phase has quasi-one-dimesional hole and electron Fermi surfaces which are almost degenerate in the momentum space corresponding to a nodal-line semimetal. Around 50 fs after the pump light arrival, pseudogap is observed at the Fermi level while it disappears to be the semimetal state around 150 fs. By means of infra-red spectroscopy under pressure, all the excitonic insulator states were found to be semimetallic under pressure.

Academic Significance and Societal Importance of the Research Achievements

励起子絶縁体Ta2NiSe5は中赤外領域に直接バンドギャップを持つ。本研究課題では、励起子絶縁体から半金属への圧力誘起相転移とパルスレーザー光による100フェムト秒スケールの光誘起相転移のメカニズムを解明した。固体物理学分野で励起子絶縁体に関連する研究が流行しつつあり、この成果は先駆的研究としてインパクトを与えている。また、層状遷移金属カルコゲナイドであるTa2NiSe5では、MoS2などのように原子層結晶によるデバイス化も期待される。デバイス化に向けた研究は未成熟な段階ではあるが、励起子絶縁体が新しいタイプの光量子デバイスへと応用される可能性を秘めていることが本研究課題によって示された。

Research Products

• [Int'l Joint Research] University of Rome "La Sapienza"/Sincrotrone Trieste S.C.p.A.(イタリア)
• [Int'l Joint Research] Rutgers University(米国)
• [Int'l Joint Research] ローマ大学(イタリア)
• [Int'l Joint Research] マックスプランク研究所(ドイツ)
• [Int'l Joint Research] Roma大学(イタリア)
• [Int'l Joint Research] Fribourg大学(スイス)
• [Journal Article] Quasi One-Dimensional Band Structure of Photoinduced Semimetal Phase of Ta_2Ni_{1-x}Co_xSe_5 (x=0.0 and 0.1) (2023)
  • Author(s): Mitsuoka Takumi、Takahashi Yu、Suzuki Takeshi、Okawa Mario、Takagi Hidenori、Katayama Naoyuki、Sawa Hiroshi、Nohara Minoru、Watanabe Mari、Xu Jiadi、Ren Qianhui、Fujisawa Masami、Kanai Teruto、Itatani Jiro、Okazaki Kozo、Shin Shik、Mizokawa Takashi
  • Journal Title: Journal of the Physical Society of Japan Volume: 92 Issue: 2 Pages: 023703-023703
  • DOI: 10.7566/jpsj.92.023703
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Robustness of Excitonic Coupling in Ta2NiSe5 Against Electronic Inhomogeneity Introduced by S Substitution for Se (2023)
  • Author(s): Masaki Hattori, Giovanni Tomassucci, Genki Hayashi, Mario Okawa, Marek Kopciuszynski, Alexey Barinov, Yangfan Lu, Hidenori Takagi, Naurang L. Saini, Takashi Mizokawa
  • Journal Title: Advanced Qunatum Technologies Volume: 6 Issue: 6 Pages: 202300034-202300034
  • DOI: 10.1002/qute.202300034
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Pressure suppression of the excitonic insulator state in Ta2NiSe5 observed by optical conductivity (2023)
  • Author(s): H. Okamura, T. Mizokawa, K. Miki, Y. Matsui, N. Noguchi, N. Katayama, H. Sawa, M. Nohara, Y. Lu, H. Takagi, Y. Ikemoto, and T. Moriwaki
  • Journal Title: Physical Review B Volume: 107 Issue: 4 Pages: 045141-045141
  • DOI: 10.1103/physrevb.107.045141
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Temporal Evolution and Fluence Dependence of Band Structure in Photoexcited Ta2Ni0.9Co0.1Se5 Probed by Time- and Angle-Resolved Photoemission Spectroscopy (2023)
  • Author(s): Yu Takahashi, Takeshi Suzuki, Masaki Hattori, Mario Okawa, Hidenori Takagi, Naoyuki Katayama, Hiroshi Sawa, Minoru Nohara, Yigui Zhong, Kecheng Liu, Teruto Kanai, Jiro Itatani, Shik Shin, Kozo Okazaki, Takashi Mizokawa
  • Journal Title: Journal of Physical Society of Japan Volume: 92
  • Peer Reviewed
• [Journal Article] Direct observation of multiple conduction-band minima in high-performance thermoelectric SnSe (2023)
  • Author(s): Okawa Mario、Akabane Yuka、Maeda Mizuki、Tan Gangjian、Zhao Li-Dong、Kanatzidis Mercouri G.、Suzuki Takeshi、Watanabe Mari、Xu Jiadi、Ren Qianhui、Fujisawa Masami、Kanai Teruto、Itatani Jiro、Shin Shik、Okazaki Kozo、Saini Naurang L.、Mizokawa Takashi
  • Journal Title: Scripta Materialia Volume: 223 Pages: 115081-115081
  • DOI: 10.1016/j.scriptamat.2022.115081
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Impact of Co or Cu Substitution for Ni on the Electronic Structure of Ta2NiSe5 Studied by Band Structure Calculations (2022)
  • Author(s): Yu Takahashi, and Takashi Mizokawa
  • Journal Title: Journal of Physical Society of Japan Volume: 91 Issue: 7 Pages: 074714-074714
  • DOI: 10.7566/jpsj.91.074714
  • Peer Reviewed
• [Journal Article] Fermi Surface Geometry of Heavily Hole Doped CaKFe4As4 Revealed by Angle-Resolved Photoemission Spectroscopy (2022)
  • Author(s): S. Hikami, S. Ishida, A. Iyo, H. Eisaki, M. Arita, S. Kumar, E. F. Schwier, K. Shimada, N. L. Saini, T. Mizokawa,
  • Journal Title: Journal of the Physical Society of Japan Volume: 91 Issue: 12 Pages: 124704-124704
  • DOI: 10.7566/jpsj.91.124704
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Domain Dependent Fermi Arcs Observed in a Striped Phase Dichalcogenide (2022)
  • Author(s): Takashi Mizokawa, Alexei Barinov, Viktor Kandyba, Alessio Giampietri, Ryoya Matsumoto, Yohei Okamoto, Kou Takubo, Koji Miyamoto, Taichi Okuda, Sunseng Pyon, Hiroyuki Ishii, Kazutaka Kudo, Minoru Nohara, Naurang L. Saini
  • Journal Title: Advanced Qunatum Technologies Volume: 5 Issue: 9 Pages: 202300029-202300029
  • DOI: 10.1002/qute.202200029
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Bulk and surface electronic structure of MnPSe3 revealed by photoemission and x-ray absorption spectroscopy (2022)
  • Author(s): Masato Fujii, Tomoyuki Yamaguchi, Takuo Ohkochi, Chandan De, Sang-Wook Cheong, and Takashi Mizokawa
  • Journal Title: Physical Review B Volume: 106 Issue: 3 Pages: 035118-035118
  • DOI: 10.1103/physrevb.106.035118
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Orbital dependent band degeneracy and edge states in single layer and AA bilayer honeycomb lattice systems with p orbital degeneracy (2022)
  • Author(s): Genki Hayashi and Takashi Mizokawa
  • Journal Title: Journal of Physics Communications Volume: 6 Issue: 8 Pages: 085011-085011
  • DOI: 10.1088/2399-6528/ac8855
  • Peer Reviewed / Open Access
• [Journal Article] Do Excitonic Insulators Exist? (2021)
  • Author(s): 溝川 貴司、岡﨑 浩三
  • Journal Title: Butsuri Volume: 76 Issue: 6 Pages: 355-359
  • DOI: 10.11316/butsuri.76.6_355
  • NAID: 130008049304
  • ISSN: 0029-0181, 2423-8872
  • Year and Date: 2021-06-05
• [Journal Article] Surface Electronic States and Inclining Surfaces in MoTe2 Probed by Photoemission Spectromicroscopy (2021)
  • Author(s): Matsumoto Ryoya、Saini Naurang L.、Giampietri Alessio、Kandyba Viktor、Barinov Alexey、Jha Rajveer、Higashinaka Ryuji、Matsuda Tatsuma D.、Aoki Yuji、Mizokawa Takashi
  • Journal Title: Journal of the Physical Society of Japan Volume: 90 Issue: 8 Pages: 084704-084704
  • DOI: 10.7566/jpsj.90.084704
  • NAID: 210000159181
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Hybridization-Gap Formation and Superconductivity in the Pressure-Induced Semimetallic Phase of the Excitonic Insulator Ta2NiSe5 (2021)
  • Author(s): Matsubayashi K、Okamura H、Mizokawa T、Katayama N、Nakano A、Sawa H、Kaneko T、Toriyama T、Konishi T、Ohta Y、Arima H、Yamanaka R、Hisada A、Okada T、Ikemoto Y、Moriwaki T、Munakata K、Nakao A、Nohara M、Lu Y、Takagi H、Uwatoko Y
  • Journal Title: Journal of the Physical Society of Japan Volume: 90 Issue: 7 Pages: 074706-074706
  • DOI: 10.7566/jpsj.90.074706
  • NAID: 40022620524
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Fermi Surface Geometry and Inhomogeneous Electronic States in Pr1.3-xLa0.7CexCuO4 (x = 0.05) with Small Superconducting Volume Fraction (2021)
  • Author(s): Matsuzawa Yu、Morita Tomohiro、Arita Masashi、Giampietri Alessio、Kandyba Viktor、Barinov Alexey、Takahashi Akira、Nagakubo Yusuke、Adachi Tadashi、Koike Yoji、Fujimori Atsushi、Saini Naurang L.、Mizokawa Takashi
  • Journal Title: Journal of the Physical Society of Japan Volume: 90 Issue: 5 Pages: 054704-054704
  • DOI: 10.7566/jpsj.90.054704
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Evolution of the Fermi surface in superconductor PrO1-xFxBiS2 (x = 0.0, 0.3, and 0.5) revealed by angle-resolved photoemission spectroscopy (2021)
  • Author(s): T. Morita, Y. Matsuzawa, S. Kumar, E. F. Schwier, K. Shimada, R. Higashinaka, T. D. Matsuda, Y. Aoki, N. L. Saini, and T. Mizokawa
  • Journal Title: Physical Review B Volume: 103 Issue: 9
  • DOI: 10.1103/physrevb.103.094510
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Detecting electron-phonon coupling during photoinduced phase transition (2021)
  • Author(s): Suzuki Takeshi、Shinohara Yasushi、Lu Yangfan、Watanabe Mari、Xu Jiadi、Ishikawa Kenichi L.、Takagi Hide、Nohara Minoru、Katayama Naoyuki、Sawa Hiroshi、Fujisawa Masami、Kanai Teruto、Itatani Jiro、Mizokawa Takashi、Shin Shik、Okazaki Kozo
  • Journal Title: Physical Review B Volume: 103 Issue: 12 Pages: 1-10
  • DOI: 10.1103/physrevb.103.l121105
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Photoinduced Phase Transition from Excitonic Insulator to Semimetal-like State in Ta2Ni1-xCoxSe5 (x = 0.10) (2020)
  • Author(s): Mitsuoka Takumi、Suzuki Takeshi、Takagi Hidenori、Katayama Naoyuki、Sawa Hiroshi、Nohara Minoru、Watanabe Mari、Xu Jiadi、Ren Qianhui、Fujisawa Masami、Kanai Teruto、Itatani Jiro、Shin Shik、Okazaki Kozo、Mizokawa Takashi
  • Journal Title: Journal of the Physical Society of Japan Volume: 89 Issue: 12 Pages: 124703-124703
  • DOI: 10.7566/jpsj.89.124703
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Momentum Dependent Band Renormalization and Surface Aging Effect on a Zone Center Electron Pocket in NaSn2As2 Revealed by Angle-Resolved Photoemission Spectroscopy (2020)
  • Author(s): Akabane Yuka、Shimaiwa Taiki、Goto Yosuke、Mizuguchi Yoshikazu、Yokoya Takayoshi、Arita Masashi、Kumar Shiv、Schwier Eike F.、Shimada Kenya、Saini Naurang L.、Mizokawa Takashi
  • Journal Title: Journal of the Physical Society of Japan Volume: 89 Issue: 11 Pages: 114707-114707
  • DOI: 10.7566/jpsj.89.114707
  • NAID: 210000158555
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Intermittent dynamics of antiferromagnetic phase in inhomogeneous iron-based chalcogenide superconductor (2020)
  • Author(s): A. Ricci, G. Campi, B. Joseph, N. Poccia, D. Innocenti, C. Gutt, M. Tanaka, H. Takeya, Y. Takano, T. Mizokawa, M. Sprung, and N. L. Saini
  • Journal Title: PHYSICAL REVIEW B Volume: 101 Issue: 2 Pages: 020508-020508
  • DOI: 10.1103/physrevb.101.020508
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Valence-bond insulator in proximity to excitonic instability (2019)
  • Author(s): Y. Chiba, T. Mitsuoka, N. L. Saini, K. Horiba, M. Kobayashi, K. Ono, H. Kumigashira, N. Katayama, H. Sawa, M. Nohara, Y. F. Lu, H. Takagi, T. Mizokawa
  • Journal Title: Physical Review B Volume: 100 Issue: 24 Pages: 245129-245129
  • DOI: 10.1103/physrevb.100.245129
  • Peer Reviewed / Int'l Joint Research
• [Presentation] 第一原理計算によるTa2Ni(Se1-xSx)5の電子状態 (2021)
  • Author(s): 服部真己, 高橋優, 溝川貴司
  • Organizer: 日本物理学会 2021年秋季大会
• [Presentation] 励起子絶縁体関連物質Ta2Ni(Se1-xSx)5の高圧赤外分光 (2021)
  • Author(s): 松井勇太, 三木克哲, 溝川貴司, 魯楊帆, 片山尚幸, 野原実, 高木英典, 森脇太郎, 池本夕佳, 岡村英一
  • Organizer: PSH-96 日本物理学会 第76回年次大会
• [Presentation] ハニカム格子d-pモデルのスピン軌道秩序と金属絶縁体転移 (2021)
  • Author(s): 林元輝, 溝川貴司
  • Organizer: 14aH2-10 日本物理学会 第76回年次大会
• [Presentation] 蜂の巣格子上のp電子系の対称性とバンド構造 (2020)
  • Author(s): 林元輝, 溝川貴司, 島岩泰暉
  • Organizer: PSD-5 日本物理学会 2020年秋季大会
• [Presentation] バンド計算によるTa2Ni1-xCoxSe5のCo 置換効果 (2020)
  • Author(s): 高橋優, 溝川貴司
  • Organizer: PSH-96 日本物理学会 2020年秋季大会
• [Presentation] CaKFe4As4の特異なフェルミ面構造 (2020)
  • Author(s): 氷上颯馬, 森綱尚輝, 溝川貴司, 石田茂之, 永崎洋, 伊豫彰, 今井基晴, 阿部英樹, 有田将司, Shiv Kumar, Eike F. Schwier, 島田賢也, N.L. Saini
  • Organizer: 9aH1-4 日本物理学会 2020年秋季大会
• [Presentation] NaSn2As2におけるバンド構造の温度依存性 (2020)
  • Author(s): 赤羽祐香, 後藤陽介, 水口佳一, 横谷尚睦, Shiv Kumar, Eike F.Schwier, 島田賢也, N.L.Saini, 溝川貴司
  • Organizer: 11aH1-1 日本物理学会 2020年秋季大会
• [Presentation] 角度分解光電子分光によるカイラル結晶IrGe4の電子状態 (2020)
  • Author(s): 島岩泰暉, 密岡拓心, 溝川貴司, 大村瑠美, 千葉優馬, 東中隆二, 松田達磨, 青木勇二, 島田賢也, Shiv Kumar, Eike F. Schwier, A. Barinov, V. Kandyba, A. Giampietri, N.L. Saini
  • Organizer: 11pH1-3 日本物理学会 2020年秋季大会
• [Presentation] 周波数領域角度分解光電子分光法によるTa2NiSe5における光誘起絶縁体金属転移の研究(実験) (2019)
  • Author(s): 鈴木剛, 篠原康, 魯楊帆, 渡邉真莉, 徐佳笛, 高木英典, 野原実, 片山尚幸, 澤博, 藤澤正美, 金井輝人, 石井順久, 板谷治郎, 溝川貴司, 石川顕一, 岡﨑浩三, 辛埴
  • Organizer: 日本物理学会2019年秋季大会
• [Presentation] 周波数領域角度分解光電子分光法によるTa2NiSe5における光誘起絶縁体金属転移の研究(理論) (2019)
  • Author(s): 篠原康, 鈴木剛, 魯楊帆, 渡邉真莉, 徐佳笛, 高木英典, 野原実, 片山尚幸, 澤博, 藤澤正美, 金井輝人, 石井順久, 板谷治郎, 溝川貴司, 石川顕一, 岡﨑浩三, 辛埴
  • Organizer: 日本物理学会2019年秋季大会
• [Presentation] 励起子絶縁体Ta2Ni1-xCoxSe5の時間分解光電子分光 (2019)
  • Author(s): 密岡拓心, 鈴木剛, 渡邉真莉, 藤澤正美, 金井輝人, 石井順久, 板谷治郎, 岡崎浩三, 辛埴, 野原実, 片山尚幸, 澤博, 魯楊帆, 高木英典, 溝川貴司
  • Organizer: 日本物理学会2019年秋季大会
• [Presentation] Ta2NiSe5のエキシトニック相と光誘起半金属相 (2019)
  • Author(s): 溝川貴司
  • Organizer: 分子研研究会「有機ディラック電子系におけるトポロジカル現象と新奇物性開拓」
  • Invited
• [Presentation] Domain-dependent electronic structure of layered transition-metal compounds probed by photoemission spectromicroscopy (2019)
  • Author(s): Takashi Mizokawa
  • Organizer: Conference on Advances in Electron Spectroscopy - Experiment and Theory
  • Int'l Joint Research / Invited
• [Funded Workshop] Electronic correlation and lattice anomaly in exotic transition-metal compounds: Multiorbital Mott/Slater phases and orbitally-induced excitonic/CDW phases (2023)
• [Funded Workshop] 2nd Italy-Japan seminar on electronic correlation and lattice anomalies in superconducting and thermoelectric materials (2020)