CaV_4O_9

• Project/Area Number: 25400357
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Condensed matter physics II
• Research Institution: Tokyo Metropolitan University (2015); The University of Tokyo (2013-2014)
• Principal Investigator: UEDA Kazuo 首都大学東京, 理工学研究科, 教授 (70114395)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Project Status: Completed (Fiscal Year 2015)
• Budget Amount: ¥4,940,000 (Direct Cost: ¥3,800,000、Indirect Cost: ¥1,140,000); Fiscal Year 2015: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000); Fiscal Year 2014: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000); Fiscal Year 2013: ¥2,470,000 (Direct Cost: ¥1,900,000、Indirect Cost: ¥570,000)
• Keywords: 強相関電子系 / 量子相転移 / 金属絶縁体転移 / ディラック電子 / スピンギャップ / 反強磁性

Outline of Final Research Achievements

The two-dimensional lattice of the CaV4O9 type is the regularly one-fifth depleted square lattice whose unit cell contains four sites. We have clarified that the Hubbard model on this lattice shows rich variety of metal-insulator transitions as well as magnetic transitions. For this purpose we use the mean field approximation at the quarter filling, while the dynamical mean field theory is employed at the half filling. Difference between the nonmagnetic semiconducting ground state of FeSi and the magnetic metallic one of FeGe is understood in the light of quantum phase transitions in the multi-orbital systems.

Research Products

• [Journal Article] Unified treatment of theory on magnetic properties of FeGe and FeSi (2016)
  • Author(s): Y. Yanagi and K. Ueda
  • Journal Title: Physical Review B Volume: 93 Issue: 4
  • DOI: 10.1103/physrevb.93.045125
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Magnetic Phases and Edge States of the 1/5-Depleted Square-Lattice (2014)
  • Author(s): Y. Yamashita, M. Tomura, Y. Yanagi, and K. Ueda.
  • Journal Title: JPS Conf. Proc. Volume: 3 Pages: 016012-016012
  • DOI: 10.7566/jpscp.3.016012
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Journal Article] Quantum Phase Transition in the 1/5-Depleted Square Lattice Hubbard Model (2014)
  • Author(s): Y. Yanagi and K. Ueda
  • Journal Title: JPS Conf. Proc. Volume: 3 Pages: 013005-013005
  • DOI: 10.7566/jpscp.3.013005
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Journal Article] Continuous Mott transition in a two-dimensional Hubbard model (2014)
  • Author(s): Y. Yanagi and K. Ueda.
  • Journal Title: Phys. Rev. B Volume: 90 Issue: 8 Pages: 085113-085113
  • DOI: 10.1103/physrevb.90.085113
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Journal Article] SU(3) Dirac Electrons in the 1/5-Depleted Square-Lattice Hubbard Model at 1/4-Filling (2013)
  • Author(s): Y. Yamashita, M. Tomura, Y. Yanagi, and K. Ueda
  • Journal Title: Phys. Rev. B Volume: 88 Issue: 19
  • DOI: 10.1103/physrevb.88.195104
  • Peer Reviewed
• [Presentation] Dynamical mean field study on magnetic properties of FeSi and FeGe (2015)
  • Author(s): Yuki Yanagi and Kazuo Ueda
  • Organizer: Second International Workshop on "Dynamical Mean-Field Approach for Strongly Correlated Materials”
  • Place of Presentation: Max Planck Institute for Chemical Physics of Solids, Dresden
  • Year and Date: 2015-09-30
  • Int'l Joint Research
• [Presentation] FeSiおよびFeGeの磁気的性質の動的平均場理論による研究 (2015)
  • Author(s): 柳有起、上田和夫
  • Organizer: 日本物理学会2015年秋季大会
  • Place of Presentation: 関西大学千里山ャンパス
  • Year and Date: 2015-09-19
• [Presentation] FeSi及びFeGeの電子状態と磁気的性質 (2015)
  • Author(s): 柳 有起、上田 和夫
  • Organizer: 日本物理学会第70回年次大会
  • Place of Presentation: 早稲田大学(東京都新宿区)
  • Year and Date: 2015-03-22
• [Presentation] 2次元ハバード模型におけるリフシッツ転移 (2014)
  • Author(s): 柳 有起、上田 和夫
  • Organizer: 日本物理学会2014年秋季大会
  • Place of Presentation: 中部大学春日井キャンパス(愛知県春日井市)
  • Year and Date: 2014-09-09
• [Presentation] 1/5欠損正方格子ハバード模型におけるSU(3)ディラック電子と磁気相図
  • Author(s): 山下靖文，都村正樹，柳有起，上田和夫
  • Organizer: 日本物理学会第69回年次大会
  • Place of Presentation: 東海大学(神奈川県平塚市)
• [Presentation] 1/5周期欠損正方格子ハバード模型における金属絶縁体転移
  • Author(s): 柳有起，上田和夫
  • Organizer: 日本物理学会第69回年次大会
  • Place of Presentation: 東海大学(神奈川県平塚市)