写真a

TAKAYOSHI Shintaro

Position

Professor

Research Field

Natural Science / Semiconductors, optical properties of condensed matter and atomic physics, Natural Science / Magnetism, superconductivity and strongly correlated systems

Homepage URL

https://sites.google.com/site/shintarotakayoshi/english_top

External Link

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Graduating School 【 display / non-display 】

  • The University of Tokyo   Faculty of Science   Graduated

    2003.4 - 2007.3

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Graduate School 【 display / non-display 】

  • The University of Tokyo   Graduate School, Division of Science   Doctor's Course   Completed

    2009.4 - 2012.3

  • The University of Tokyo   Graduate School, Division of Science   Master's Course   Completed

    2007.4 - 2009.3

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Studying abroad experiences 【 display / non-display 】

  • 2018.9
    -
    2020.3

    Max Planck Institute for the Physics of Complex Systems  

  • 2015.9
    -
    2018.9

    University of Geneva  

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Campus Career 【 display / non-display 】

  • KONAN UNIVERSITY   Faculty of Science and Engineering   Faculty of Science and Engineering Department of Physics   Professor

    2025.4

  • KONAN UNIVERSITY   Faculty of Science and Engineering   Faculty of Science and Engineering Department of Physics   Associate Professor

    2020.4 - 2025.3

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External Career 【 display / non-display 】

  • Max Planck Institute for the Physics of Complex Systems

    2018.9 - 2020.3

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    Country：Germany

  • Max Planck Institute for the Physics of Complex Systems

    2018.9 - 2020.3

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    Country：Germany

  • University of Geneva   Department of Quantum Matter Physics

    2015.9 - 2018.9

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    Country：Switzerland

  • The University of Tokyo   School of Science, Department of Physics

    2015.5 - 2015.8

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    Country：Japan

  • National Institute for Materials Science

    2013.4 - 2015.4

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    Country：Japan

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Research Career 【 display / non-display 】

  • Theory of ultrafast spintronics driven by laser fields

    Project Year： 2020.4  -   

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Papers 【 display / non-display 】

  • Many-body Keldysh crossover in the dc-driven Haldane spin chain Reviewed International journal

    Koichi Okazaki, Shun Okumura, Shintaro Takayoshi, Takashi Oka

    Physical Review B   111 ( 23 )   235422   2025.6

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    Joint Work

    Publisher：American Physical Society (APS)  

    We theoretically investigate nonlinear processes driven by a DC spin-electric field in the antiferromagnetic spin-1 Heisenberg model with the system initially in its ground state (the Haldane phase). The DC spin-electric field generates finite spin current and spin accumulation because the field destroys the symmetry-protected topological order. We identify two microscopic mechanisms responsible for the breakdown as well as the crossover between these mechanisms: In weak fields, tripron-antitripron pair creation occurs through the tunneling mechanism, and in strong fields, the system is described by an effective Hamiltonian in which the protecting symmetries are broken. We analyze the numerical results using the Dykhne-Davis-Pechukas theory and the Floquet theory, verifying the universal picture of the many-body Keldysh crossover in DC-driven quantum spin systems.

    DOI： 10.1103/hml5-p6cw

  • Many-Body Effects on High-Harmonic Generation in Hubbard Ladders Reviewed International coauthorship

    Yuta Murakami, Thomas Hansen, Shintaro Takayoshi, Lars Bojer Madsen, Philipp Werner

    Physical Review Letters   134 ( 9 )   096504   2025.3

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    Joint Work

    Publisher：American Physical Society (APS)  

    We unveil multifaceted effects of spin-charge couplings on the high-harmonic generation (HHG) in Mott insulators by analyzing the two-leg ladder Hubbard model, where spin dynamics activated by the interchain hopping ty drastically modifies the HHG features. When the two chains are decoupled (ty=0), HHG originates from the dynamics of coherent doublon-holon pairs because of spin-charge separation. With increasing ty, the doublon-holon pairs lose their coherence due to their interchain hopping and resultant nonlocal spin strings. Furthermore, the HHG signal from spin polarons—charges dressed by spin clouds—leads to an additional plateau in the HHG spectrum. For large ty, we identify unconventional HHG processes involving three elementary excitations—two polarons and one magnon. Our study is an essential step toward a microscopic understanding of nontrivial many-body effects on HHG in correlated materials beyond conventional semiconductors.

    DOI： 10.1103/physrevlett.134.096504

    Other Link： http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevLett.134.096504/fulltext

  • Phase transitions and spin dynamics of the quasi-one dimensional Ising-like antiferromagnet BaCo2V2O8 in a longitudinal magnetic field Reviewed International coauthorship International journal

    Shintaro Takayoshi, Quentin Faure, Virginie Simonet, Béatrice Grenier, Sylvain Petit, Jacques Ollivier, Pascal Lejay, Thierry Giamarchi

    Physical Review Research   5 ( 2 )   023205   2023.6

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    Joint Work

    Authorship：Lead author,　Corresponding author   Publisher：American Physical Society (APS)  

    By combining inelastic neutron scattering and numerical simulations, we study the quasi-one-dimensional Ising-like quantum antiferromagnet BaCo2⁢V2⁢O8
    in a longitudinal magnetic field applied along the Ising anisotropy, which is also the chain direction. The external field closes the excitation gap due to the magnetic anisotropy, inducing a transition from the Néel ordered state to an incommensurate longitudinal spin density wave phase. If the field is increased further, another transition into a transverse antiferromagnetic phase takes place at 9 T due to the competition between longitudinal and transverse correlations. We numerically and experimentally show that the model of XXZ chains connected by a weak interchain interaction well reproduces this transition. We also calculate the dynamical susceptibility and demonstrate that it agrees quantitatively with inelastic neutron scattering measurements. In contrast to the abrupt change of magnetic ordering, the spectra do not change much at the transition at 9 T, and the spin dynamics can be described as a Tomonaga-Luttinger liquid. We also refine the modeling of BaCo2⁢V2⁢O8
    by including a four-site periodic term arising from the crystal structure which enables one to account for an anomaly of the magnetic susceptibility appearing at 19.5 T, as well as for the anticrossing observed in the inelastic neutron scattering spectra.

    DOI： 10.1103/physrevresearch.5.023205

    Other Link： http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevResearch.5.023205/fulltext

  • Spin, Charge, and η-Spin Separation in One-Dimensional Photodoped Mott Insulators Reviewed International coauthorship International journal

    Yuta Murakami, Shintaro Takayoshi, Tatsuya Kaneko, Andreas M. Läuchli, Philipp Werner

    Physical Review Letters   130 ( 10 )   106501   2023.3

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    Joint Work

    Publisher：American Physical Society (APS)  

    We show that effectively cold metastable states in one-dimensional photodoped Mott insulators described by the extended Hubbard model exhibit spin, charge, and η-spin separation. Their wave functions in the large on-site Coulomb interaction limit can be expressed as |Ψ>=|Ψcharge>|Ψspin>|Ψη-spin>, which is analogous to the Ogata-Shiba states of the doped Hubbard model in equilibrium. Here, the η-spin represents the type of photo-generated pseudoparticles (doublon or holon). |Ψcharge> is determined by spinless free fermions, |Ψspin> by the isotropic Heisenberg model in the squeezed spin space, and |Ψη-spin> by the XXZ model in the squeezed η-spin space. In particular, the metastable η-pairing and charge-density-wave (CDW) states correspond to the gapless and gapful states of the XXZ model. The specific form of the wave function allows us to accurately determine the exponents of correlation functions. The form also suggests that the central charge of the η-pairing state is 3 and that of the CDW phase is 2, which we numerically confirm. Our study provides analytic and intuitive insights into the correlations between active degrees of freedom in photodoped strongly correlated systems.

    DOI： 10.1103/PhysRevLett.130.106501

    Other Link： https://link.aps.org/article/10.1103/PhysRevLett.130.106501

  • Mott memristors based on field-induced carrier avalanche multiplication Reviewed International coauthorship International journal

    Francesco Peronaci, Sara Ameli, Shintaro Takayoshi, Alexandra S. Landsman, Takashi Oka

    Physical Review B   107 ( 7 )   075154   2023.2

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    Joint Work

    Publisher：American Physical Society (APS)  

    We present a theory of Mott memristors whose working principle is the nonlinear carrier avalanche multiplication in Mott insulators subject to strong electric fields. The internal state of the memristor, which determines its resistance, is encoded in the density of doublon and hole excitations in the Mott insulator. In the current-voltage characteristic, insulating and conducting states are separated by a negative-differential-resistance region, leading to hysteretic behavior. Under oscillating voltage, the response of a voltage-controlled, nonpolar memristive system is obtained, with retarded current and pinched hysteresis loop. As a first step towards neuromorphic applications, we demonstrate self-sustained spiking oscillations in a circuit with a parallel capacitor. Being based on electronic excitations only, this memristor is up to several orders of magnitude faster than previous proposals relying on Joule heating or ionic drift.

    DOI： 10.1103/PhysRevB.107.075154

    Other Link： http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevB.107.075154/fulltext

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Review Papers (Misc) 【 display / non-display 】

  • コタイ ブツリ 〈 キタエフスピン エキタイ ノ シン テンカイ 〉 トクシュウゴウ ; ダイナミクス ト シンキ ブッセイ

    57 ( 11 )   713 - 724   2022.11

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  • Laser control of magnonic topological phases in antiferromagnets

    Nakata Kouki, Kim Se Kwon, Takayoshi Shintaro

    Meeting Abstracts of the Physical Society of Japan   75.1   1372 - 1372   2020

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    Publisher：The Physical Society of Japan  

    DOI： 10.11316/jpsgaiyo.75.1.0_1372

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  • Spinon confinement and quantum phase transition in quasi-one-dimensional antiferromagnets

    Takayoshi Shintaro, Furuya Shunsuke C., Giamarchi Thierry

    Meeting Abstracts of the Physical Society of Japan   74.1   1215 - 1215   2019

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    Publisher：The Physical Society of Japan  

    DOI： 10.11316/jpsgaiyo.74.1.0_1215

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  • Field theoretical approach to the entanglement spectrum of AKLT states

    Tanaka Akihiro, Takayoshi Shintaro

    Meeting Abstracts of the Physical Society of Japan   72 ( 0 )   2419 - 2419   2017

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    Publisher：The Physical Society of Japan  

    DOI： 10.11316/jpsgaiyo.72.2.0_2419

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  • Theoretical Study towards Ultrafast Spintronics

    Sato Masahiro, Takayoshi Shintaro, Oka Takashi

    Butsuri   72 ( 11 )   783 - 792   2017

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    Publisher：The Physical Society of Japan  

    <p>In this article, we explain our theoretical proposals, ultrafast ways of controlling magnetic properties of solid (magnetization, spin chirality, spin currents, etc.) by laser. We first review the Floquet theorem, which is useful for the prediction of novel laser-induced phenomena, then we turn to our recent results. We cover the following topics: laser-induced magnetization growing process, laser-driven spin chirality and spin current in multiferroics, and topological spin liquid state realized by laser in the honeycomb Kitaev model.</p>

    DOI： 10.11316/butsuri.72.11_783

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Presentations 【 display / non-display 】

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Grant-in-Aid for Scientific Research 【 display / non-display 】

  • Real and reciprocal spacetime imaging of many-body excitons and quantum phase control

    2024.4 - 2028.3

    JSPS Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research(A)

  • Theoretical study of quantum computation in topological magnets

    2022.4 - 2025.3

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

  • Search for novel states in disordered systems induced by external field driving

    2021.4 - 2024.3

    JSPS Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research(C)

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