Phase Transition and Crossover in Dynamically Correlated Electron Systems

2010 Fiscal Year Self-evaluation Report

• Project Area: Optical science of dynamically correlated electrons in semiconductors
• Project/Area Number: 20104010
• 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: Osaka University
• Principal Investigator: ASANO Kenichi Osaka University, 大学院・理学研究科, 准教授 (10379274)
• Project Period (FY): 2008 – 2012
• Keywords: 電子正孔系 / 励起子 / モット転移 / BCS-BECクロスオーバー / FFLO相 / ディラック電子系 / 量子ホール系

Research Abstract

電子と正孔が同数共存する系の熱平衡状態は、物性物理学の縮図と言える程の多様性を示すことが理論的に予言されている。実際、励起子気体相(低密度かつ低温)と電子正孔プラズマ相(高温または高密度)の間には励起子モット転移があり、極低温では量子凝縮が起き、励起子BEC(励起子のボーズ凝縮)、電子正孔BCS(電子正孔クーパー対の凝縮)相が現れる。この系は、相関効果や多体効果を考察する絶好の理論研究の舞台を与えるだけでなく、半導体レーザーをはじめとする応用面においても重要である。そこで、旧来の摂動論を越え、相関効果まで考慮した半定量的な理論の構築を目指す。
また、アンバランスな電子正孔二層系で起こる新奇な量子凝縮相、セミメタルと半導体の中間に位置しているDirac電子系(グラフェンやカーボンナノチューブ系)の光学応答に対する相互作用効果、電子正孔系との関連が深い多軌道ハバードモデルといった新しいテーマの開拓にも取り組む。

Research Products

• [Journal Article] Designing Dirac points in two-dimensional lattices (2011)
  • Author(s): K.Asano, C.Hotta
  • Journal Title: to be published in Physical Review B
  • Peer Reviewed
• [Journal Article] Biexcitons in semiconducting single-walled carbon nanotubes (2011)
  • Author(s): K.Watanabe, K.Asano
  • Journal Title: Physical Review B 83 Pages: 115406-1-115406-5
  • Peer Reviewed
• [Journal Article] Mott transition in the Hubbard model on the anisotropic kagome lattice (2010)
  • Author(s): Y.Furukawa, T.Ohashi, Y.Koyama, N.Kawakami
  • Journal Title: Physical Review B 82 Pages: 161101-1-161101-4(R
  • Peer Reviewed
• [Journal Article] Quantum Condensation in electron.Hole Bilayers with Density Imbalance (2010)
  • Author(s): K.Yamashita, K.Asano, T.Ohashi
  • Journal Title: Journal of the Physics Society of Japan 79 Pages: 033001-1-033001-4
  • Peer Reviewed
• [Journal Article] Cellular Dynamical Mean Field Study on Two-Orbital Hubbard Model with Different Bandwidths (2010)
  • Author(s): T.Kita, T.Ohashi, S.Suga
  • Journal Title: Journal of Physical Society of Japan 79 Pages: 014713-1-014713-5
  • Peer Reviewed
• [Presentation] Spectral lineshapes of cyclotron resonance in monolayer and bilayer grapheme (2010)
  • Author(s): K.Asano, T.Ando
  • Organizer: The 19th International Conference on the Application of High Magnetic Fields in Semiconductor Physics and Nanotechnology (HMF-19)
  • Place of Presentation: 福岡国際会議場(福岡県)
  • Year and Date: 2010-08-03
• [Presentation] Screening effect to biexciton in carbon nanotubes (2010)
  • Author(s): K.Watanabe, K.Asano
  • Organizer: The 16th International Conference on Superlattices, Nanostructures and Nanodevices (ICSNN-2010)
  • Place of Presentation: 北京(中国)
  • Year and Date: 2010-07-20
• [Presentation] Ground state of electron-hole bilayer with density imbalance (2010)
  • Author(s): K.Yamashita, T.Ohashi, K.Asano
  • Organizer: The 9th International Conference on Excitonic and Photonic Processes in Condensed and Nano Materials (EXCON'10)
  • Place of Presentation: Brisbane (Australia)
  • Year and Date: 2010-07-14
• [Presentation] Approximate validity of Kohn ' s theorem in cyclotron resonance in grapheme (2009)
  • Author(s): K.Asano, T.Ando
  • Organizer: The 18th International Conference on Electronic Properties of Two-Dimensional Systems (EP2DS-18)
  • Place of Presentation: 神戸コンベンションセンター(兵庫県)
  • Year and Date: 2009-07-23
• [Presentation] Quantum Condensation in the electron-hole system with density imbalance (2009)
  • Author(s): K.Yamashita, K.Asano, T.Ohashi, T.Ogawa
  • Organizer: The 18th International Conference on Electronic Properties of Two-Dimensional Systems (EP2DS-18)
  • Place of Presentation: 神戸コンベンションセンター(兵庫県)
  • Year and Date: 2009-07-21