Updated on 2022/04/12

写真a

 
NAKANO Akitoshi
 
Organization
Graduate School of Science Assistant Professor
Graduate School
Graduate School of Science
Undergraduate School
School of Science Department of Physics
Title
Assistant Professor
External link

Degree 1

  1. 博士(工学) ( 2018.12   名古屋大学 ) 

Research Interests 2

  1. 構造物性

  2. 強相関電子系

Research Areas 1

  1. Natural Science / Magnetism, superconductivity and strongly correlated systems  / thermoelectric, semimetal, semiconductor, excitonic insulator, dielectric, structural physics

Current Research Project and SDGs 2

  1. Exploring a novel semimetallic thermoelectrics

  2. 励起子絶縁体の輸送特性の研究

Research History 1

  1. 名古屋大学大学院   理学研究科物質理学専攻V研究室   助教

    2019.1

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    Country:Japan

Education 2

  1. Nagoya University   Graduate School, Division of Engineering

    2016.4 - 2018.12

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    Country: Japan

  2. Nagoya University   Faculty of Engineering

    2010.4 - 2014.3

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    Country: Japan

Professional Memberships 1

  1. 日本物理学会

 

Papers 22

  1. Giant Peltier conductivity in an uncompensated semimetal Ta2PdSe6 Reviewed

    Nakano Akitoshi, Yamakage Ai, Maruoka Urara, Taniguchi Hiroki, Yasui Yukio, Terasaki Ichiro

    JOURNAL OF PHYSICS-ENERGY   Vol. 3 ( 4 )   2021.9

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    Authorship:Lead author, Corresponding author   Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1088/2515-7655/ac2357

    Web of Science

  2. Room Temperature Thermoelectric Properties of Isostructural Selenides Ta2PdS6 and Ta2PdSe6 Reviewed

    Nakano Akitoshi, Maruoka Urara, Kato Fumiaki, Taniguchi Hiroki, Terasaki Ichiro

    Journal of the Physical Society of Japan   Vol. 90 ( 3 ) page: 33702 - 33702   2021.3

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    Authorship:Lead author   Publisher:Physical Society of Japan  

  3. High-Pressure Thermopower of the Mott Insulator Ca<inf>2</inf>RuO<inf>4</inf> Reviewed

    Sano I., Nakano T., Nakano A., Taniguchi H., Nakamura F., Terasaki I.

    Journal of the Physical Society of Japan   Vol. 91 ( 3 )   2022.3

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Journal of the Physical Society of Japan  

    We have measured and analyzed the thermopower of single-crystal samples of the Mott insulator Ca2RuO4 in high pressure up to 0.9 GPa. We find that the thermopower rapidly changes at a metal-insulator transition temperature, which is explained in terms of a percolation theory. In contrast, the thermopower in the insulator phase slightly decreases with increasing pressure well below the transition temperature, and is associated with thermodynamic quantities through the Kelvin formula. The pressure dependence is compared with the current-density dependence, and a possible origin for the current-enhanced thermopower is proposed.

    DOI: 10.7566/JPSJ.91.033703

    Scopus

  4. Charge and Lattice Dynamics in Excitonic Insulator Ta2NiSe5 Investigated Using Ultrafast Reflection Spectroscopy

    Miyamoto Tatsuya, Mizui Makoto, Takamura Naoki, Hirata Junya, Yamakawa Hiromichi, Morimoto Takeshi, Terashige Tsubasa, Kida Noriaki, Nakano Akitoshi, Sawa Hiroshi, Okamoto Hiroshi

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   Vol. 91 ( 2 )   2022.2

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    Language:Japanese   Publisher:Journal of the Physical Society of Japan  

    An excitonic insulator, in which an optical gap is formed by exciton condensation, is expected to exhibit large photoresponses. Here, we report the results of femtosecond reflection spectroscopy covering a wide infrared region on a typical excitonic insulator, Ta2NiSe5, which gives direct information not only about a change of excitonic gap but also a metallization. With a weak excitation, the excitonic gap decreases due to the weakening of excitonic effect by photocarriers. With a strong excitation, a Drude-like high-reflection band appears, showing an excitonic-insulator-to-metal transition. Analyses of spectral and temporal changes of reflectivity revealed that the metallization is accompanied by large structural changes. This demonstrates an important role of electron–lattice interaction on the stabilization of excitonic phase.

    DOI: 10.7566/JPSJ.91.023701

    Web of Science

    Scopus

  5. A large piezoelectric voltage coefficient in aluminate-sodalite-type improper ferroelectric oxides Reviewed

    Taniguchi Hiroki, Hattori Taiga, Isobe Toshihiro, Nakano Akitoshi, Terasaki Ichiro, Hagiwara Manabu

    JOURNAL OF MATERIALS CHEMISTRY C     2021.10

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1039/d1tc03897d

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  6. Ga-substitution effects on the improper ferroelectric phase transition of Ca<inf>8</inf>[AlO<inf>2</inf>]<inf>12</inf>(MoO<inf>4</inf>)<inf>2</inf> Reviewed

    Maruyama K., Nakano A., Terasaki I., Taniguchi H.

    Open Ceramics   Vol. 5   2021.3

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Open Ceramics  

    The aluminum-sodalite-type oxide, Ca8[AlO2]12(MoO4)2, shows an improper ferroelectricity below a ferroelectric phase transition temperature around 630 ​K. Here we present effects of a Ga-substitution for Al on ferroelectric properties of Ca8[AlO2]12(MoO4)2. Systematic investigations with synchrotron x-ray powder diffractions and dielectric/pyroelectric measurements have clarified that the Ga-substitution suppresses the ferroelectricity and markedly enhances a thermal hysteresis of the ferroelectric phase transition. In contrast to the case of Sr-substitution for Ca, with which the ground state results in a relaxor-like state, the polar ordering of macroscopic scale has been found to survive under the Ga-substitution. The present results shed light on intuitive designing of ferroelectricity and the phase transition properties in the aluminum-sodalite-type oxide.

    DOI: 10.1016/j.oceram.2021.100080

    Scopus

  7. Examination of Nonlinear Conductivity on the Excitonic Insulator Candidate Ta2NiSe5 Reviewed

    Nakano Akitoshi, Maruoka Urara, Taniguchi Hiroki, Terasaki Ichiro

    Journal of the Physical Society of Japan   Vol. 89 ( 4 ) page: 45001 - 45001   2020.4

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    Authorship:Lead author, Corresponding author   Language:English   Publisher:Physical Society of Japan  

  8. Exciton Transport in the Electron–Hole System Ta₂NiSe₅ Reviewed

    Nakano Akitoshi, Nagai Takayuki, Katayama Naoyuki, Sawa Hiroshi, Taniguchi Hiroki, Terasaki Ichiro

    Journal of the Physical Society of Japan   Vol. 88 ( 11 ) page: 113706 - 1-4   2019.11

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    Authorship:Lead author, Corresponding author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:日本物理学会  

    We have measured the dielectric constant and thermopower of single crystal samples of the excitonic insulator candidate Ta2NiSe5. The dielectric constant below 50 K shows relaxor-like relaxation, implying the existence of randomly distributed electric dipoles. We have evaluated the concentration of the dipoles to be 10^19 cm^−3 at 30 K, which gives a rough estimate of the exciton concentration in this compound. A large thermopower of 600 µV/K at 100 K suddenly drops toward zero down to 50 K, and this zero thermopower evidences the neutral particles flow against the applied temperature gradient. We have semi-quantitatively explained the above two anomalies in terms of spontaneously generated excitons at low temperatures where thermally excited holes are quenched.ファイル公開:2020/11/15

  9. Antiferroelectric distortion with anomalous phonon softening in the excitonic insulator Ta2NiSe5 Reviewed

    Nakano Akitoshi, Hasegawa Takumi, Tamura Shinya, Katayama Naoyuki, Tsutsui Satoshi, Sawa Hiroshi

    PHYSICAL REVIEW B   Vol. 98 ( 4 )   2018.7

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    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1103/PhysRevB.98.045139

    Web of Science

    Scopus

  10. Pressure-induced coherent sliding-layer transition in the excitonic insulator Ta2NiSe5

    Nakano Akitoshi, Sugawara Kento, Tamura Shinya, Katayama Naoyuki, Matsubayashi Kazuyuki, Okada Taku, Uwatoko Yoshiya, Munakata Kouji, Nakao Akiko, Sagayama Hajime, Kumai Reiji, Sugimoto Kunihisa, Maejima Naoyuki, Machida Akihiko, Watanuki Tetsu, Sawa Hiroshi

    IUCRJ   Vol. 5 ( Pt 2 ) page: 158-165   2018.3

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    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1107/S2052252517018334

    Web of Science

    Scopus

    PubMed

  11. Hybridization-Gap Formation and Superconductivity in the Pressure-Induced Semimetallic Phase of the Excitonic Insulator Ta₂NiSe₅ Reviewed

    Matsubayashi Kazuyuki, Okamura Hidekazu, Mizokawa Takashi, Katayama Naoyuki, Nakano Akitoshi, Sawa Hiroshi, Kaneko Tatsuya, Toriyama Tatsuya, Konishi Takehisa, Ohta Yukinori, Arima Hiroto, Yamanaka Rina, Hisada Akihiko, Okada Taku, Ikemoto Yuka, Moriwaki Taro, Munakata Koji, Nakao Akiko, Nohara Minoru, Lu Yangfan, Takagi Hidenori, Uwatoko Yoshiya

    Journal of the Physical Society of Japan   Vol. 90 ( 7 ) page: 74706 - 1-6   2021.7

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    Language:English   Publishing type:Research paper (scientific journal)  

  12. Unconventional high-temperature ferromagnetic semiconductor PbPd1-x-yFeyLixO2 Reviewed

    He Yangchen, Sato Daiki, Misawa Kazuki, Nishihara Daiki, Kimura Akinori, Nakano Akitoshi, Taniguchi Hiroki, Terasaki Ichiro

    JOURNAL OF APPLIED PHYSICS   Vol. 129 ( 20 )   2021.5

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1063/5.0051283

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    Scopus

  13. Coexisting Mechanisms for the Ferroelectric Phase Transition in Li2SrNb2O7 Reviewed

    Mochizuki Yasuhide, Nagai Takayuki, Shirakuni Hirokazu, Nakano Akitoshi, Oba Fumiyasu, Terasaki Ichiro, Taniguchi Hiroki

    CHEMISTRY OF MATERIALS   Vol. 33 ( 4 ) page: 1257 - 1264   2021.2

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Chemistry of Materials  

    DOI: 10.1021/acs.chemmater.0c04032

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    Scopus

  14. Permittivity boosting in "yellow" (Nb plus In) co-doped TiO2 Reviewed

    Taniguchi Hiroki, Sato Daiki, Nakano Akitoshi, Terasaki Ichiro

    JOURNAL OF MATERIALS CHEMISTRY C   Vol. 8 ( 39 ) page: 13627 - 13631   2020.10

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Journal of Materials Chemistry C  

    DOI: 10.1039/d0tc03539d

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    Scopus

  15. Non-equilibrium Steady State in the Mott Insulator Ca2RuO4 Reviewed

    Terasaki Ichiro, Sano Isuzu, Toda Kosuke, Kawasaki Shuji, Nakano Akitoshi, Taniguchi Hiroki, Cho Hai Jun, Ohta Hiromichi, Nakamura Fumihiko

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   Vol. 89 ( 9 )   2020.9

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Journal of the Physical Society of Japan  

    DOI: 10.7566/JPSJ.89.093707

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    Scopus

  16. Intercalated Cu+ ion dynamics in the two-dimensional layered compound Cu0.33TiSe2 Reviewed

    Kitou Shunsuke, Hasegawa Takumi, Nakano Akitoshi, Katayama Naoyuki, Tsutsui Satoshi, Sawa Hiroshi

    PHYSICAL REVIEW B   Vol. 101 ( 9 )   2020.3

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    Language:English   Publisher:Physical Review B  

    DOI: 10.1103/PhysRevB.101.094108

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  17. Phase Transition from Weak Ferroelectricity to Incipient Ferroelectricity in Li2Sr(Nb1-xTax)(2)O-7 Reviewed

    Nagai Takayuki, Mochizuki Yasuhide, Shirakuni Hirokazu, Nakano Akitoshi, Oba Fumiyasu, Terasaki Ichiro, Taniguchi Hiroki

    CHEMISTRY OF MATERIALS   Vol. 32 ( 2 ) page: 744 - 750   2020.1

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1021/acs.chemmater.9b04022

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  18. Measuring the conduction band of Ta<sub>2</sub>NiSe<sub>5</sub> using low energy inverse photoelectron spectroscopy

    Kawamura Keita, Terasaki Ichiro, Yoshida Hiroyuki, Sato Haruki, Orio Hibiki, Sugimoto Koudai, Ohta Yukinori, Ootsuki Daiki, Yoshida Teppei, Maruoka Urara, Nakano Akitoshi

    Abstract book of Annual Meeting of the Japan Society of Vacuum and Surface Science   Vol. 2020 ( 0 )   2020

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    Publisher:The Japan Society of Vacuum and Surface Science  

    <p>Ta<sub>2</sub>NiSe<sub>5</sub> is a candidate for the excitonic insulator. Recent photoemission study revealed that the valence band minimum shifts to the low energy side at low temperature, which is consistent with the excitonic insulator. To confirm this, it is necessary to observe the conduction band. In this study, we examined the conduction band of Ta<sub>2</sub>NiSe<sub>5</sub> using the low energy inverse photoelectron spectroscopy (LEIPS). The lowest unoccupied band was observed at 0.55 eV above the Fermi level. This band did not shift at the low temperature of 80 K. This result supports the recent proposed picture that the Ta<sub>2</sub>NiSe<sub>5</sub> is different from the conventional excitonic insulator; the noninteracting band structure is a band-overlap semimetal and the bandgap opens by the strong electron-hole attraction.</p>

    DOI: 10.14886/jvss.2020.0_135

  19. Weak Ferroelectricity in n=2 Pseudo Ruddlesden-Popper-Type Niobate Li2SrNb2O7 Reviewed

    Nagai Takayuki, Shirakuni Hirokazu, Nakano Akitoshi, Sawa Hiroshi, Moriwake Hiroki, Terasaki Ichiro, Taniguchi Hiroki

    CHEMISTRY OF MATERIALS   Vol. 31 ( 16 ) page: 6257 - 6261   2019.8

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1021/acs.chemmater.9b02373

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  20. Effect of Cu intercalation and pressure on excitonic interaction in 1T-TiSe2 Reviewed

    Kitou S., Nakano A., Kobayashi S., Sugawara K., Katayama N., Maejima N., Machida A., Watanuki T., Ichimura K., Tanda S., Nakamura T., Sawa H.

    PHYSICAL REVIEW B   Vol. 99 ( 10 )   2019.3

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1103/PhysRevB.99.104109

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  21. A novel red-emitting K2Ca(PO4)F:Eu2+ phosphor with a large Stokes shift

    Daicho H., Shinomiya Y., Enomoto K., Nakano A., Sawa H., Matsuishi S., Hosono H.

    CHEMICAL COMMUNICATIONS   Vol. 54 ( 8 ) page: 884-887   2018.1

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1039/c7cc08202a

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  22. Nanocomposite Phosphor Consisting of CaI2:Eu2+ Single Nanocrystals Embedded in Crystalline SiO2

    Daicho Hisayoshi, Iwasaki Takeshi, Shinomiya Yu, Nakano Akitoshi, Sawa Hiroshi, Yamada Wataru, Matsuishi Satoru, Hosono Hideo

    ACS APPLIED MATERIALS & INTERFACES   Vol. 9 ( 47 ) page: 41405-41412   2017.11

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1021/acsami.7b14132

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Presentations 3

  1. Huge Power factor in a transition metal chalcogenide Ta2PdSe6

    2020.3.15 

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    Language:Japanese   Presentation type:Oral presentation (general)  

  2. Structural analyses in Ruddlesden-Popper-type Li2SrNb2O7 using synchrotron X-ray diffraction experiments International conference

    A. Nakano, T. Nagai, H. Sawa, I. Terasaki, and H. Taniguchi

    PACRIM13 

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    Event date: 2019.10 - 2019.11

    Language:English   Presentation type:Oral presentation (general)  

    Venue:Okinawa   Country:Japan  

  3. 励起子絶縁体候補物質Ta2NiSe5における非線形伝導現象の観測

    中埜彰俊, 丸岡うらら, 谷口博基, 寺崎一郎

    日本物理学会 

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    Event date: 2019.9

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:岐阜大学   Country:Japan  

KAKENHI (Grants-in-Aid for Scientific Research) 2

  1. 強い非補償伝導を示す熱電半金属の合成と物性測定

    Grant number:21K13878  2021.4 - 2023.3

    科学研究費助成事業  若手研究

    中埜 彰俊

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    Authorship:Principal investigator 

    Grant amount:\4680000 ( Direct Cost: \3600000 、 Indirect Cost:\1080000 )

    最近、申請者は層状カルコゲナイドTa2PdSe6が15 Kで巨大な熱電応答を示すことを発見した。本研究ではその起源解明と制御を目指す。室温以下で高い性能を示す熱電物質は限られており、またそれらはバンドギャップの小さな縮退半導体や強相関金属が主であった。それに対してTa2PdSe6は半金属であり、何らかの起源により電子と正孔の熱電応答が相殺しない“非補償”な電気伝導が実現していると考えなければこの巨大応答は説明できない。本研究では、異種元素を置換した一連の単結晶における熱電特性計測に基づき機能性の発現機構を実験的に明らかにし、半金属を用いた低温熱電という新しい指針を提案する。

  2. Function creation in polar metals

    Grant number:21H01030  2021.4 - 2024.3

    Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (B)

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    Authorship:Coinvestigator(s) 

 

Teaching Experience (On-campus) 2

  1. Experiment

    2020

  2. 3年学生実験

    2019