• Search Research Projects
  • Search Researchers
  • How to Use
  1. Back to previous page

Stability and control of topological nature of quasiparticles emerging in quantum spin liquids

Publicly Offered Research

Project AreaFrontiers of materials science spun from topology
Project/Area Number 18H04223
Research Category

Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)

Allocation TypeSingle-year Grants
Research InstitutionYokohama National University

Principal Investigator

那須 譲治  横浜国立大学, 大学院工学研究院, 准教授 (40610639)

Project Period (FY) 2018-04-01 – 2020-03-31
Project Status Completed (Fiscal Year 2019)
Budget Amount *help
¥3,900,000 (Direct Cost: ¥3,000,000、Indirect Cost: ¥900,000)
Fiscal Year 2019: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000)
Fiscal Year 2018: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000)
Keywords量子スピン液体 / トポロジカル量子物性 / トポロジカル物性
Outline of Annual Research Achievements

本年度では、量子スピン液体において現れる創発準粒子を制御する方法を理論提案することを目的に研究を進めてきた。それを達成するため具体的にはキタエフ量子スピン液体を考える。そこで現れる創発準粒子は磁場で制御できると考えられるため、磁場効果を詳しく調べた。低磁場領域では、マヨラナ準粒子を素励起に持つ量子スピン液体が実現するが、磁場を強くしていくと、スピン波であるマグノンを素励起に持つ強制強磁性状態へと変化する。これらがどのように繋がるかを解析するために、量子モンテカルロ法を主に用いて、厳密対角化法、スピン波近似法などを併用することで、素励起のダイナミクスを計算した。
さらに、創発準粒子を実験的に捉えるために、実験の研究グループとの共同研究も行った。例えば、ラマン散乱を用いることで、ストークス及びアンチストークス散乱スペクトルからからマグノン励起とは全く異なる散乱強度のエネルギー及び温度依存性が現れることがわかった。この結果は、キタエフ量子スピン液体を実現する候補物質である塩化ルテニウムにおいてマヨラナ準粒子の存在を示唆するものと考えられる。
また、核磁気共鳴実験においても、塩化ルテニウムにおいて緩和率に2種類のギャップの存在を示唆する結果が得られており、この結果は、スピンが2種類の準粒子に分数化していることを反映していることが期待される。
これらの研究を通して、創発準粒子を観測する方法に関しては明らかになりつつあるが、制御する方法については、まだ研究途上であるといわざるを得ないので、ここで得られた成果をもとに、準粒子を制御する実現可能な方法の確立を目指して研究を継続していく。

Research Progress Status

令和元年度が最終年度であるため、記入しない。

Strategy for Future Research Activity

令和元年度が最終年度であるため、記入しない。

Report

(2 results)
  • 2019 Annual Research Report
  • 2018 Annual Research Report
  • Research Products

    (29 results)

All 2020 2019 2018 Other

All Int'l Joint Research (2 results) Journal Article (18 results) (of which Int'l Joint Research: 4 results,  Peer Reviewed: 18 results,  Open Access: 3 results) Presentation (9 results) (of which Int'l Joint Research: 6 results,  Invited: 6 results)

  • [Int'l Joint Research] University of Tennessee/Oak Ridge National Laboratory/Boston College(米国)

    • Related Report
      2019 Annual Research Report
  • [Int'l Joint Research] Imperial College London(英国)

    • Related Report
      2019 Annual Research Report
  • [Journal Article] Hunting Majorana Fermions in Kitaev Magnets2020

    • Author(s)
      Motome Yukitoshi、Nasu Joji
    • Journal Title

      Journal of the Physical Society of Japan

      Volume: 89 Issue: 1 Pages: 012002-012002

    • DOI

      10.7566/jpsj.89.012002

    • NAID

      210000157849

    • Related Report
      2019 Annual Research Report
    • Peer Reviewed / Open Access
  • [Journal Article] Two-step gap opening across the quantum critical point in the Kitaev honeycomb magnet α?RuCl32020

    • Author(s)
      Nagai Yuya、Jinno Takaaki、Yoshitake Junki、Nasu Joji、Motome Yukitoshi、Itoh Masayuki、Shimizu Yasuhiro
    • Journal Title

      Physical Review B

      Volume: 101 Issue: 2 Pages: 020414-020414

    • DOI

      10.1103/physrevb.101.020414

    • Related Report
      2019 Annual Research Report
    • Peer Reviewed / Int'l Joint Research
  • [Journal Article] Spin transport in the Quantum Spin Liquid State in the S=1 Kitaev model: role of the fractionalized quasiparticles2020

    • Author(s)
      A. Koga, T. Minakawa, Y. Murakami, and J. Nasu
    • Journal Title

      J. Phys. Soc. Jpn.

      Volume: 89 Issue: 3 Pages: 33701-33701

    • DOI

      10.7566/jpsj.89.033701

    • NAID

      40022185595

    • Related Report
      2019 Annual Research Report
    • Peer Reviewed
  • [Journal Article] The range of non-Kitaev terms and fractional particles in α-RuCl32020

    • Author(s)
      Wang Yiping、Osterhoudt Gavin B.、Tian Yao、Lampen-Kelley Paige、Banerjee Arnab、Goldstein Thomas、Yan Jun、Knolle Johannes、Ji Huiwen、Cava Robert J.、Nasu Joji、Motome Yukitoshi、Nagler Stephen E.、Mandrus David、Burch Kenneth S.
    • Journal Title

      npj Quantum Materials

      Volume: 5 Issue: 1 Pages: 14-14

    • DOI

      10.1038/s41535-020-0216-6

    • Related Report
      2019 Annual Research Report
    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Journal Article] Majorana-magnon crossover by a magnetic field in the Kitaev model: Continuous-time quantum Monte Carlo study2020

    • Author(s)
      Yoshitake Junki、Nasu Joji、Kato Yasuyuki、Motome Yukitoshi
    • Journal Title

      Physical Review B

      Volume: 101 Issue: 10 Pages: 100408-100408

    • DOI

      10.1103/physrevb.101.100408

    • Related Report
      2019 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Low temperature properties in the Bilayer Kitaev model2019

    • Author(s)
      H. Tomishige, J. Nasu, and A. Koga
    • Journal Title

      Phys. Rev. B

      Volume: 99 Issue: 17 Pages: 1744241-5

    • DOI

      10.1103/physrevb.99.174424

    • Related Report
      2019 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Ferromagnetic Instability for single-band Hubbard model in the strong-coupling regime2019

    • Author(s)
      Y. Kamogawa, J. Nasu, and A. Koga
    • Journal Title

      Phys. Rev. B

      Volume: 99 Issue: 23 Pages: 2351071-6

    • DOI

      10.1103/physrevb.99.235107

    • Related Report
      2019 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Residual entropy and spin fractionalizations in the mixed-spin Kitaev model2019

    • Author(s)
      A. Koga and J. Nasu
    • Journal Title

      Phys. Rev. B

      Volume: 100 Issue: 10 Pages: 1004041-5

    • DOI

      10.1103/physrevb.100.100404

    • Related Report
      2019 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Nonequilibrium Majorana dynamics by quenching a magnetic field in Kitaev spin liquids2019

    • Author(s)
      Nasu Joji、Motome Yukitoshi
    • Journal Title

      Physical Review Research

      Volume: 1 Issue: 3 Pages: 033007-033007

    • DOI

      10.1103/physrevresearch.1.033007

    • Related Report
      2019 Annual Research Report
    • Peer Reviewed / Open Access
  • [Journal Article] Symmetry breaking states in the half-filled two-orbital Hubbard model with crystalline electric field2019

    • Author(s)
      K. Ishigaki, J. Nasu, and A. Koga
    • Journal Title

      J. Phys. Soc. Jpn.

      Volume: 88 Issue: 2 Pages: 0247021-5

    • DOI

      10.7566/jpsj.88.024702

    • NAID

      210000135099

    • Related Report
      2018 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Staggered ordered phases in the three-orbital Hubbard model2019

    • Author(s)
      K. Ishigaki, J. Nasu, A. Koga, S. Hoshino, and P. Werner
    • Journal Title

      Phys. Rev. B

      Volume: 99 Issue: 8 Pages: 0851311-11

    • DOI

      10.1103/physrevb.99.085131

    • Related Report
      2018 Annual Research Report
    • Peer Reviewed / Int'l Joint Research
  • [Journal Article] Quantum and classical behavior of spin-S Kitaev models in the anisotropic limit2019

    • Author(s)
      Minakawa Tetsuya、Nasu Joji、Koga Akihisa
    • Journal Title

      Physical Review B

      Volume: 99 Issue: 10 Pages: 104408-104408

    • DOI

      10.1103/physrevb.99.104408

    • Related Report
      2018 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Ground-state and thermodynamic properties of an S=1 Kitaev model2018

    • Author(s)
      A. Koga, H. Tomishige, and J. Nasu
    • Journal Title

      J. Phys. Soc. Jpn.

      Volume: 87 Issue: 6 Pages: 0637031-4

    • DOI

      10.7566/jpsj.87.063703

    • NAID

      210000134846

    • Related Report
      2018 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Unusual thermal Hall effect in a Kitaev spin liquid candidate α-RuCl32018

    • Author(s)
      Y. Kasahara, K. Sugii, T. Ohnishi, M. Shimozawa, M. Yamashita, N. Kurita, H. Tanaka, J. Nasu, Y. Motome, T. Shibauchi, and Y. Matsuda
    • Journal Title

      Phys. Rev. Lett.

      Volume: 120 Issue: 21 Pages: 217205-217205

    • DOI

      10.1103/physrevlett.120.217205

    • Related Report
      2018 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Magnetoelectric Effect in a Spin-State Transition System2018

    • Author(s)
      Naka Makoto、Mizoguchi Eriko、Nasu Joji、Ishihara Sumio
    • Journal Title

      Journal of the Physical Society of Japan

      Volume: 87 Issue: 6 Pages: 063709-063709

    • DOI

      10.7566/jpsj.87.063709

    • NAID

      210000134852

    • Related Report
      2018 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Majorana quantization and half-integer thermal quantum Hall effect in a Kitaev spin liquid2018

    • Author(s)
      Kasahara Y.、Ohnishi T.、Mizukami Y.、Tanaka O.、Ma Sixiao、Sugii K.、Kurita N.、Tanaka H.、Nasu J.、Motome Y.、Shibauchi T.、Matsuda Y.
    • Journal Title

      Nature

      Volume: 559 Issue: 7713 Pages: 227-231

    • DOI

      10.1038/s41586-018-0274-0

    • NAID

      120006497340

    • Related Report
      2018 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Successive Majorana topological transitions driven by a magnetic field in the Kitaev model2018

    • Author(s)
      Nasu Joji、Kato Yasuyuki、Kamiya Yoshitomo、Motome Yukitoshi
    • Journal Title

      Physical Review B

      Volume: 98 Issue: 6 Pages: 060416-060416

    • DOI

      10.1103/physrevb.98.060416

    • Related Report
      2018 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Spontaneously orbital-selective superconductivity in a three-orbital Hubbard model2018

    • Author(s)
      K. Ishigaki, J. Nasu, A. Koga, S. Hoshino, and P. Werner
    • Journal Title

      Phys. Rev. B

      Volume: 98 Issue: 23 Pages: 2351201-7

    • DOI

      10.1103/physrevb.98.235120

    • Related Report
      2018 Annual Research Report
    • Peer Reviewed / Int'l Joint Research
  • [Presentation] Nonequilibrium dynamics induced by magnetic-field quench in Kitaev spin liquids with fractional Majorana excitations2019

    • Author(s)
      J. Nasu and Y. Motome
    • Organizer
      International Conference on Strongly Correlated Electron Systems 2019
    • Related Report
      2019 Annual Research Report
    • Int'l Joint Research
  • [Presentation] Magnetic-field effect and transport properties in Kitaev spin liquids2019

    • Author(s)
      J. Nasu
    • Organizer
      3rd EPiQS-TMS alliance workshop on Topological Phenomena in Quantum Materials (TPQM2019)
    • Related Report
      2019 Annual Research Report
    • Int'l Joint Research / Invited
  • [Presentation] Nonequilibrium dynamics in Kitaev spin liquids with fractional Majorana quasiparticles2019

    • Author(s)
      J. Nasu
    • Organizer
      The 3rd Asia-Pacific workshop on Quantum Magnetism
    • Related Report
      2019 Annual Research Report
    • Int'l Joint Research / Invited
  • [Presentation] Nonequilibrium dynamics of Kitaev spin liquids with fractional Majorana excitations2019

    • Author(s)
      J. Nasu
    • Organizer
      International Conference on Topological Material Science 2019
    • Related Report
      2019 Annual Research Report
    • Int'l Joint Research
  • [Presentation] Non-equilibrium dynamics by field quench in Kitaev model2019

    • Author(s)
      J. Nasu and Y. Motome
    • Organizer
      Symposium: Topological Phases and Functionality of Correlated Electron Systems (2019)
    • Related Report
      2018 Annual Research Report
    • Int'l Joint Research
  • [Presentation] キタエフ模型における磁場効果2019

    • Author(s)
      那須譲治
    • Organizer
      第4回TMS領域研究会
    • Related Report
      2018 Annual Research Report
    • Invited
  • [Presentation] キタエフ量子スピン液体におけるマヨラナ準粒子2019

    • Author(s)
      那須譲治
    • Organizer
      量子多体系の素核・物性クロスオーバー
    • Related Report
      2018 Annual Research Report
    • Invited
  • [Presentation] Majorana topological transition driven by a magnetic field in the Kitaev model2018

    • Author(s)
      J. Nasu
    • Organizer
      TMS-PKU 2nd Alliance Workshop
    • Related Report
      2018 Annual Research Report
    • Int'l Joint Research / Invited
  • [Presentation] Kitaevスピン液体の有限温度ダイナミクスと輸送現象2018

    • Author(s)
      那須譲治
    • Organizer
      基研研究会「スピン系物理の最前線」
    • Related Report
      2018 Annual Research Report
    • Invited

URL: 

Published: 2018-04-23   Modified: 2021-01-27  

Information User Guide FAQ News Terms of Use Attribution of KAKENHI

Powered by NII kakenhi