Shirahama, Keiya

写真a

Affiliation

Faculty of Science and Technology, Department of Physics （Yagami）

Position

Professor

Related Websites

External Links
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Career 【 Display / hide 】

  • 1990.04
    -
    1991.03

    Japan Society for Promotion of Science, Postdoctoral researcher

  • 1990.04
    -
    1991.03

    Japan Society for Promotion of Science, Doctoral researcher

  • 1991.04
    -
    1991.06

    University of Bayreuth, Research associate

  • 1991.07
    -
    1993.03

    Bundesrepulik Deutschland, Alexander von Humboldt Stiftung, Stipendiat (Universitaet Bayreuth)

  • 1993.04
    -
    1999.03

    University of Tokyo, Institute for Solid State Physics, Research associate

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Academic Background 【 Display / hide 】

  • 1985.03

    Hokkaido University, Faculty of Science, 物理学科

    University, Graduated

  • 1987.03

    Hokkaido University, Graduate School, Division of Natural Science, Physics

    Graduate School, Completed, Master's course

  • 1990.03

    The University of Tokyo, Graduate School, Division of Science, Physics

    Graduate School, Completed, Doctoral course

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Academic Degrees 【 Display / hide 】

  • 理学博士, The University of Tokyo, Coursework, 1990.03

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Research Areas 【 Display / hide 】

  • Natural Science / Magnetism, superconductivity and strongly correlated systems (Low Temperature Physics)

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Research Keywords 【 Display / hide 】

  • Helium

  • Low Dimensional Electron System

  • Scanning Probe Microscopy

  • Superfluidity

  • Quantum Phase Transition

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Research Themes 【 Display / hide 】

  • Quantum Phenomena of Helium Confined in Nano-Porous Media, 

    2000
    -
    2009

  • Superfluidity of Solid Helium 4, 

    2005
    -
    2009

  • Development of Low-temperature Scanning Probe Microscope, 

    2004
    -
    2009

  • Two-dimensional Electrons on Liquid Helium Surfaces, 

    1999
    -
    2009

  • Laser Cooling of Metastable Helium Atoms, 

    2001
    -
    2010

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Books 【 Display / hide 】

  • Topology in Ordered Phases

    Keiya Shirahama, Keiichi Yamamoto, Yoshiyuki Shibayama, 2006.11

    Scope: 227-234

    　View Summary

    著者が発見した、ナノ多孔体中ヘリウム4の量子相転移に関する総合報告。

  • 現代物理最前線6

    SHIRAHAMA KEIYA, 共立出版株式会社, 2002.10

    Scope: 61-128

    　View Summary

    固体基盤などの表面に束縛されたヘリウム3は、ユニークな2次元量子流体として振る舞う。この2次元量子流体の、最近の研究で明らかになった興味深い性質の数々を非専門家向けに解説した。

  • 2-D Electron Systems on Helium and Other Substrates

    Kimitoshi Kono, Keiya Shirahama (edited by E. Y. Andrei), Kluwer Academic Pub., 1997.07

    Scope: 175-189

    　View Summary

    液体ヘリウム表面上2次元電子系に関する総合報告。著者らが発見した、液体ヘリウム4表面上ウィグナー結晶の磁場中非線形電気伝導現象について解説している。

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Papers 【 Display / hide 】

  • Reply to "comment on 'Effect of rotation on the elastic moduli of solid He 4 ' "

    Tsuiki T., Takahashi D., Murakawa S., Okuda Y., Kono K., Shirahama K.

    Physical Review B （Physical Review B)  99 （ 6 ）  2019.02

    ISSN  24699950

    　View Summary

    © 2019 American Physical Society. We respond to the Comment by Pushkarov. We find that, in solid He4, He3 impurity atoms that pin dislocation segments are not impuritons, but randomly walking particles. The interpretation for the rotation effect, which was based on the impuriton model, does have to be totally reconsidered, taking into account the motion of randomly walking He3 in the strong elastic potential near the core of edge dislocations.

  • Elastic anomaly of thin neon film

    Makiuchi T., Yamashita K., Tagai M., Nago Y., Shirahama K.

    Journal of the Physical Society of Japan （Journal of the Physical Society of Japan)  88 （ 3 ）  2019

    ISSN  00319015

    　View Summary

    © 2019 The Physical Society of Japan. Adsorbed molecular films provide two-dimensional systems that show various emergent phenomena that are not observed in bulk counterparts. We have measured the elasticity of thin neon films adsorbed on porous glass down to 1 K by the torsional oscillator technique. The shear modulus of a neon film anomalously increases at low temperatures with excess dissipation. This behavior indicates a crossover from a soft (fluidlike) state at high temperatures to a stiff (solidlike) state at low temperatures. The temperature dependence of the anomaly is qualitatively similar to that of the elastic anomaly of helium films found in our recent study. The dissipation peak temperature, however, becomes constant at about 5 K, contrary to the case of helium, in which it decreases to 0 K at a critical coverage of a quantum phase transition between a gapped localized phase and a mobile (superfluid) phase. It is concluded that neon films behave as a classical system that does not show a quantum phase transition or superfluidity, although the films may be strongly supercooled to temperatures much lower than the bulk triple point, 24.6 K. Our results suggest that the elastic anomaly is a universal phenomenon of atomic or molecular films adsorbed on disordered substrates.

  • Elastic Anomaly of Helium Films at a Quantum Phase Transition

    Takahiko Makiuchi, Michihiro Tagai, Yusuke Nago, Daisuke Takahashi, and Keiya Shirahama

    Physical Review B （American Physical Society)  98 （ 23 ）  2018.12

    Research paper (scientific journal), Joint Work, Accepted,  ISSN  24699950

    　View Summary

    Helium films show various quantum phases that undergo quantum phase transitions by changing coverage n. We found anomalous elastic phenomena in bosonic 4He and fermionic 3He films adsorbed on a glass substrate. The films stiffen under AC strain at low temperature with an excess dissipation. The onset temperature of the stiffening decreases to 0 K as n approaches a critical coverage n_c . The elastic anomaly is explained by thermal activation of helium atoms from the localized to extended states with a distributed energy gap. We determine for the first time the energy band structure of helium films from elasticity. The ground states of 4He and 3He at n < n_c are identically gapped and compressible, which are possibly a sort of Mott insulator or Mott glass.

  • Reinvestigation of the rotation effect in solid 4He with a rigid torsional oscillator

    J. Choi, T. Tsuiki, D. Takahashi, H. Choi, K. Kono, K. Shirahama, and E. Kim

    Physical Review B （American Physical Society)  98   014509 2018.07

    Research paper (scientific journal), Joint Work, Accepted

    　View Summary

    We reexamined the rotation-induced effect observed in solid 4He by using a rigid two-frequency torsional oscillator (TO). The previous rotation experiments reported the rotation-induced suppression of the “nonclassical” TO response that was interpreted as evidence of irrotational bulk superfluidity in solid 4He. However, the experiment employed a nonrigid TO that could amplify the elastic contribution in the TO response. Thus, it is important to clarify if the rotation-induced suppression of the TO response could be attributed to an unavoidable elastic effect. In our rigid TO, complicated nonlinear viscoelastic contributions are systematically eliminated. In addition, the TO operating at two different resonant frequencies allows us to decompose a possible superfluidlike frequency-independent contribution on period drop from that of the linear elastic overshoot effect. We found no substantial rotation-induced effect in the out-of-phase resonant mode unlike that found in the previous rotation experiments. It indicates that the previous rotation effect in the nonrigid TO cannot be attributed to the genuine supersolidity. According to the frequency analysis of the TO response, the frequency-dependent period drop, which can be attributed to the elastic overshoot effect, remains unaffected upon application of dc rotation. However, the frequency-independent superfluidlike contribution exhibits a strikingly different rotation effect that is currently inexplicable.

  • Reinvestigation of the rotation effect in solid He 4 with a rigid torsional oscillator

    Choi J., Tsuiki T., Takahashi D., Choi H., Kono K., Shirahama K., Kim E.

    Physical Review B （Physical Review B)  98 （ 1 ）  2018.07

    ISSN  24699950

    　View Summary

    © 2018 American Physical Society. We reexamined the rotation-induced effect observed in solid He4 by using a rigid two-frequency torsional oscillator (TO). The previous rotation experiments reported the rotation-induced suppression of the "nonclassical" TO response that was interpreted as evidence of irrotational bulk superfluidity in solid He4. However, the experiment employed a nonrigid TO that could amplify the elastic contribution in the TO response. Thus, it is important to clarify if the rotation-induced suppression of the TO response could be attributed to an unavoidable elastic effect. In our rigid TO, complicated nonlinear viscoelastic contributions are systematically eliminated. In addition, the TO operating at two different resonant frequencies allows us to decompose a possible superfluidlike frequency-independent contribution on period drop from that of the linear elastic overshoot effect. We found no substantial rotation-induced effect in the out-of-phase resonant mode unlike that found in the previous rotation experiments. It indicates that the previous rotation effect in the nonrigid TO cannot be attributed to the genuine supersolidity. According to the frequency analysis of the TO response, the frequency-dependent period drop, which can be attributed to the elastic overshoot effect, remains unaffected upon application of dc rotation. However, the frequency-independent superfluidlike contribution exhibits a strikingly different rotation effect that is currently inexplicable.

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Papers, etc., Registered in KOARA 【 Display / hide 】

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Presentations 【 Display / hide 】

  • バルク液体4Heの横音響インピーダンス測定

    SHIRAHAMA KEIYA

    日本物理学会第73回年次大会, 

    2018.03
    , 

    Oral presentation (general)

  • 多孔質ガラスに吸着したネオン薄膜の弾性測定

    SHIRAHAMA KEIYA

    日本物理学会第73回年次大会, 

    2018.03
    , 

    Oral presentation (general)

  • Nanomechanical Resonator based on Carbon Nanotube for Study of Superfluid He

    SHIRAHAMA KEIYA

    The International Workshop on Electrons and Ions in Quantum Fluids and Solids, 

    2018.03
    , 

    Poster presentation

  • Quantum phase transition of thin helium films probed by elastic measurement

    SHIRAHAMA KEIYA

    The International Workshop on Electrons and Ions in Quantum Fluids and Solids, 

    2018.03
    , 

    Poster presentation

  • Toward the direct observation of chiral edge mass current in quasi-2D 3He-A

    SHIRAHAMA KEIYA

    The International Workshop on Electrons and Ions in Quantum Fluids and Solids, 

    2018.03
    , 

    Poster presentation

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Research Projects of Competitive Funds, etc. 【 Display / hide 】

  • Search for the Kondo effect in liquid helium-3

    2023.06
    -
    2025.03

    挑戦的研究（萌芽）, Principal investigator

  • Helium Spintronics

    2021.07
    -
    2023.03

    MEXT,JSPS, Grant-in-Aid for Scientific Research, Grant-in-Aid for Challenging Research (Exploratory), Principal investigator

  • Novel Quantum Phenomena in 2D Helium with Aspects of Quantum Phase Transition

    2020.04
    -
    2023.03

    MEXT,JSPS, Grant-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (A) , Principal investigator

  • フォノン照射による原子分子薄膜の超流動化

    2019.06
    -
    2021.03

    MEXT,JSPS, Grant-in-Aid for Scientific Research, Grant-in-Aid for Challenging Research (Exploratory) , Principal investigator

  • ヘリウム薄膜における量子弾性効果と超固体現象の解明

    2017.04
    -
    2019.03

    日本学術振興会, Grant-in-Aid for Scientific Research, Research grant, Principal investigator

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Awards 【 Display / hide 】

  • Sir Martin Wood Prize

    SHIRAHAMA KEIYA, 2001.11, ミレニアム・サイエンス・フォーラム, Transport Phenomena of the Wigner Crystal on a Superfluid 3He Surface

    Type of Award： International academic award (Japan or overseas)

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Courses Taught 【 Display / hide 】

  • SOLID STATE PHYSICS 3

    2024

  • PHYSICS LABORATORIES 2

    2024

  • PHYSICS LABORATORIES 1

    2024

  • LOW TEMPERATURE PHYSICS

    2024

  • LITERATURE OF PHYSICS

    2024

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Social Activities 【 Display / hide 】

  • 日本学術会議　連携会員

    2017.10
    -
    2020.09

  • 日本学術振興会学術システム研究センター　専門研究員

    2015.04
    -
    2018.03

    　View Summary

    日本学術振興会学術システム研究センターの数物系科学班専門研究員として、科学研究費関連の業務を遂行する。

  • 国立大学法人　東京大学物性研究所

    2008.04
    -
    2010.03

  • Institute for solid state physics, University of Tokyo

    2008.04
    -
    2010.03
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Memberships in Academic Societies 【 Display / hide 】

  • The Japan Society on Adsorption, 

    2018.11
    -
    Present

  • Cryogenics and Superconductivity Society of Japan, 

    2016.04
    -
    Present

  • Japanese Society of Applied Physics, 

    1998.04
    -
    2028.03

  • American Physical Society, 

    1993.04
    -
    Present

  • 日本物理学会, 

    1986.03
    -
    2028.03
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Committee Experiences 【 Display / hide 】

  • 2018.04
    -
    2020.03

    協議会委員, 国立大学法人　東京大学物性研究所

  • 2017.10
    -
    2020.09

    連携会員, 日本学術会議

  • 2017.04
    -
    2019.03

    受賞候補等推薦委員会委員, 日本物理学会

  • 2017.03
    -
    2019.03

    代議員, 日本物理学会

  • 2015.04
    -
    2018.03

    数物系科学専門研究員, 日本学術振興会学術システム研究センター

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