Theoretical and Numerical Studhy on the Multipole Orders and Novel Conductivity of the Frustrated Systems

• Project Area: J-Physics: Physics of conductive multipole systems
• Project/Area Number: 16H01080
• Research Category: Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)
• Allocation Type: Single-year Grants
• Review Section: Science and Engineering
• Research Institution: University of Hyogo
• Principal Investigator: 坂井 徹 兵庫県立大学, 物質理学研究科, 教授 (60235116)
• Project Period (FY): 2016-04-01 – 2018-03-31
• Project Status: Completed (Fiscal Year 2017)
• Budget Amount: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000); Fiscal Year 2017: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000); Fiscal Year 2016: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
• Keywords: 量子スピン系 / フラストレーション系 / 低次元磁性体 / スピンネマティック相 / スピンラダー系 / フラストレーション / スピン・ネマティック / スピン多極子 / 多極子 / スピンネマティック / スピンラダー / スピン多極子秩序

Outline of Annual Research Achievements

近年、量子スピン系における多極子秩序のひとつとして、スピンネマティック相が注目されている。とくに低次元磁性体やフラストレーション系において、理論的に予測され、最近になって候補物質による検証実験が盛んに行われているが、まだスピンネマティック相が実験的に発見されたという確証には至っていない場合が多い。本研究代表者による従来の研究により、容易軸異方性を持つ擬一次元反強磁性体のスピンフロップ現象では、通常の一次相転移による磁化ジャンプの代わりに、２回の二次相転移が生じ、その中間相としてスピンネマティック相が出現することが理論的・数値的に示されている。そこで、本研究では、この予測されるスピンネマティック相を伴う磁場誘起相転移がおきる可能性の高い候補物質をいくつか提唱し、検証実験の提案を行った。一方、本研究では、これとは別に、二本鎖の一方が強磁性相互作用、他方が反強磁性相互作用を持つようなスピンラダー系にも着目し、理論的・計算科学的研究を行った。その結果、この系は特定のパラメーター領域においては、厳密なエネルギー固有状態を求めることができること、またその一部は厳密な基底状態になっていることを導くことに成功した。さらに、この系に大規模数値対角化及び密度行列繰り込み群の手法を適用して数値的に解析した結果、本研究の重要な目的のひとつである新しいスピンネマティック相の理論予測をすることに成功した。この成果により、スピンネマティック相の実験的探索を試みる候補物質として、スピンラダー系にも幅を広げることができた。

Research Progress Status

29年度が最終年度であるため、記入しない。

Strategy for Future Research Activity

29年度が最終年度であるため、記入しない。

Research Products

• [Journal Article] Spin-1/2 Triangular-Lattice Heisenberg Antiferromagnet with √3×√3-Type Distortion --- Behavior around the Boundaries of the Intermediate Phase (2018)
  • Author(s): Alisa Shimada, Hiroki Nakano, Toru Sakai, and Kazuyoshi Yoshimura
  • Journal Title: Journal of the Physical Society of Japan Volume: 87 Issue: 3 Pages: 034706-034706
  • DOI: 10.7566/jpsj.87.034706
  • NAID: 40021491789
  • Peer Reviewed / Open Access
• [Journal Article] The <i>S</i> = 1/2 Heisenberg Antiferromagnet on a Triangular Lattice with √3 × √3-Type Distortion—Magnetization Process and Magnetic Susceptibility— (2018)
  • Author(s): 嶋田ありさ, 中野博生, 坂井徹, 吉村一良
  • Journal Title: Journal of the Japan Society of Powder and Powder Metallurgy Volume: 65 Issue: 1 Pages: 3-9
  • DOI: 10.2497/jjspm.65.3
  • NAID: 130006336331
  • ISSN: 0532-8799, 1880-9014
  • Peer Reviewed
• [Journal Article] Quantum phase transition in the twisted three-leg spin tube (2017)
  • Author(s): Ito Keisuke、Yokoo Shun、Okamoto Kiyomi、Sakai Toru
  • Journal Title: Polyhedron Volume: 136 Pages: 42-44
  • DOI: 10.1016/j.poly.2017.05.024
  • NAID: 130006708986
  • Peer Reviewed
• [Journal Article] Exact Ground States of Frustrated Quantum Spin Systems Consisting of Spin-Dimer Units (2017)
  • Author(s): Toshiya Hikihara, Takashi Tonegawa, Kiyomi Okamoto, and Toru Sakai
  • Journal Title: Journal of Physical Society of Japan Volume: 86 Issue: 5 Pages: 054709-054709
  • DOI: 10.7566/jpsj.86.054709
  • NAID: 210000134369
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Journal Article] Frustrated S=1/2 Two-Leg Ladder with Different Leg Interactions (2017)
  • Author(s): Takashi Tonegawa, Kiyomi Okamoto, Toshiya Hikihara, and Toru Sakai
  • Journal Title: Journal of Physics: Conference Series Volume: 828 Pages: 012003-012003
  • DOI: 10.1088/1742-6596/828/1/012003
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Journal Article] Ferrimagnetism in the Spin-1/2 Heisenberg Antiferromagnet on a Distorted Triangular Lattice (2017)
  • Author(s): Hiroki Nakano and Toru Sakai
  • Journal Title: Journal of the Physical Society of Japan Volume: 86 Issue: 6 Pages: 063702-063702
  • DOI: 10.7566/jpsj.86.063702
  • NAID: 40021221634
  • Peer Reviewed / Open Access
• [Journal Article] Quantum Spin Liquid in the Kagome-Lattice Antiferromagnet and Related Systems (2017)
  • Author(s): H. Nakano and T. Sakai
  • Journal Title: Journal of Physics: Conference Series Volume: 868 Pages: 012006-012006
  • DOI: 10.1088/1742-6596/868/1/012006
  • Peer Reviewed / Open Access
• [Journal Article] Magnetization Process of the Spin-1/2 Triangular-Lattice Heisenberg Antiferromagnet with Next-Nearest-Neighbor Interactions --- Plateau or Nonplateau --- (2017)
  • Author(s): Hiroki Nakano and Toru Sakai
  • Journal Title: Journal of the Physical Society of Japan Volume: 86 Issue: 11 Pages: 114705-114705
  • DOI: 10.7566/jpsj.86.114705
  • NAID: 40021377012
  • Peer Reviewed / Open Access
• [Journal Article] Dzyaloshinsky-Moriya Interaction and the Ground State in S=3/2 Perfect Kagome Lattice Antiferromagnet KCr3(OH)6(SO4)2 (Cr-Jarosite) Studied by X-Band and High-Frequency ESR (2017)
  • Author(s): S. Okubo, R. Nakata, S. Idehara, N. Takahashi, T. Sakurai, W. Zhang, H. Ohta, T. Shimokawa, T. Sakai, K. Okuta, S. Hara, and H. Sato
  • Journal Title: Journal of the Physical Society of Japan Volume: 86 Issue: 2 Pages: 024703-024703
  • DOI: 10.7566/jpsj.86.024703
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Gapless Quantum Spin Liquid of the Kagome-Lattice Antiferromagnet (2017)
  • Author(s): T. Sakai and H. Nakano
  • Journal Title: POLYHEDRON Volume: 126 Pages: 42-44
  • DOI: 10.1016/j.poly.2017.01.012
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Ground State Phase Diagram of the Bond-Alternating S=2 Quantum Spin Chain with the XXZ and On-Site Anisotropies -Symmetry Protected Topological Phase versus Trivial Phase- (2016)
  • Author(s): K. Okamoto, T. Tonegawa and T. Sakai
  • Journal Title: Journal of the Physical Society of Japan Volume: 85 Issue: 6 Pages: 063704-063704
  • DOI: 10.7566/jpsj.85.063704
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Ground-state phase diagram of an anisotropic S=1/2 ladder with alternating rung interactions (2016)
  • Author(s): Takashi Tonegawa, Kiyomi Okamoto, Toshiya Hikihara and Toru Sakai
  • Journal Title: Journal of Physics: Conference Series Volume: 683 Pages: 012039-012039
  • DOI: 10.1088/1742-6596/683/1/012039
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Journal Article] Effect of monomer-monomer interactions on the phase diagrams of the S=1/2 distorted diamond type quantum spin chain (2016)
  • Author(s): K. Okamoto, T. Tonegawa and T. Sakai
  • Journal Title: Journal of Physics: Conference Series Volume: 683 Pages: 012038-012038
  • DOI: 10.1088/1742-6596/683/1/012038
  • Peer Reviewed / Open Access
• [Presentation] Gapless Quantum Spin Liquid of the Kagome-Lattice Antiferromagnet (2018)
  • Author(s): T. Sakai, H. Nakano
  • Organizer: アメリカ物理学会マーチミーティング
  • Int'l Joint Research
• [Presentation] Numerical Diagonalization Study on Frustrated Magnets (2017)
  • Author(s): T. Sakai
  • Organizer: Workshop on Quantum Dynamics and Response
  • Place of Presentation: University of Tokyo（東京都文京区）
  • Year and Date: 2017-03-13
  • Int'l Joint Research / Invited
• [Presentation] Quantum Spin Fluid Behaviors of the Kagome- and Triangular-Lattice Antiferromagnets (2017)
  • Author(s): T. Sakai, H. Nakano
  • Organizer: International Conference on Low-Temperature Physics
  • Int'l Joint Research / Invited
• [Presentation] 磁化率の計算によるスピンギャップ解析 (2017)
  • Author(s): 坂井徹、中野博生
  • Organizer: 東京大学物性研究所短期研究会 物性研究所スパコン共同利用・CCMS合同研究会「計算物質科学の今と未来」
• [Presentation] 低次元量子磁性体におけるスピンネマティック相の理論的研究 (2017)
  • Author(s): 坂井徹
  • Organizer: 東京大学物性研究所 J-Physics トピカルミーティング「局在多極子と伝導電子の相関による新現象」
• [Presentation] Gapless Spin Excitations in the Kagome- and Triangular-Lattice Antiferromagnets (2017)
  • Author(s): T. Sakai, H. Nakano
  • Organizer: International Conference on Strongly Correlated Electron Systems
  • Int'l Joint Research
• [Presentation] Spin-Nematic and Spin-Liquid Phases in Low-Dimensional Antiferromagnets (2017)
  • Author(s): T. Sakai
  • Organizer: International Workshop on Multipole Physics and Related Phenomena
  • Int'l Joint Research
• [Presentation] Gapless Quantum Spin Liquid of Kagome-Lattice Antiferromagnet (2017)
  • Author(s): T. Sakai, H. Nakano
  • Organizer: Junjiro Kanamori Memorial International Symposium -New Horizon of Magnetism-
  • Int'l Joint Research
• [Presentation] Quantum Spin Liquid of Kagome-Lattice Antiferromagnet (2017)
  • Author(s): T. Sakai, H. Nakano
  • Organizer: Symposium on Trends in Condensed Matter Physics
  • Int'l Joint Research
• [Presentation] Quantum Spin Nanotubes (2016)
  • Author(s): T. Sakai
  • Organizer: Energy, Materials, Nanotechnology Meeting
  • Place of Presentation: Mantra Bell City Hotel(Melbourne, Australia)
  • Year and Date: 2016-10-10
  • Int'l Joint Research / Invited
• [Presentation] Quantum Spin Fluid of the S=1/2 Kagome-Lattice Antiferromagnet (2016)
  • Author(s): T. Sakai
  • Organizer: International Conference on Highly Frustrated Magnetism
  • Place of Presentation: 台湾大学会議場（台湾・台北市）
  • Year and Date: 2016-09-07
  • Int'l Joint Research
• [Presentation] Quantum Spin Fluid in S=1/2 Kagome-Lattice Antiferromagnet (2016)
  • Author(s): T. Sakia
  • Organizer: STATPHYS2016
  • Place of Presentation: Palais des Congres(Lyon, France)
  • Year and Date: 2016-07-18
  • Int'l Joint Research
• [Presentation] Quantum Critical Properties of the Twisted Quantum Spin Nanotube (2016)
  • Author(s): T. Sakai
  • Organizer: International Conference on Science and Technology of Synthetic
  • Place of Presentation: 広州白雲国際会議センター（中国・広州）
  • Year and Date: 2016-06-26
  • Int'l Joint Research