低次元系における電子格子相互作用ダイナミクスの実験的解明

• Project Area: Science of Atomic Layer Systems
• Project/Area Number: 26107517
• 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: Yokohama National University
• Principal Investigator: 片山 郁文 横浜国立大学, 工学(系)研究科(研究院), 准教授 (80432532)
• Project Period (FY): 2014-04-01 – 2016-03-31
• Project Status: Completed (Fiscal Year 2015)
• Budget Amount: ¥7,020,000 (Direct Cost: ¥5,400,000、Indirect Cost: ¥1,620,000); Fiscal Year 2015: ¥3,510,000 (Direct Cost: ¥2,700,000、Indirect Cost: ¥810,000); Fiscal Year 2014: ¥3,510,000 (Direct Cost: ¥2,700,000、Indirect Cost: ¥810,000)
• Keywords: カーボンナノチューブ / グラフェン / コヒーレントフォノン / 電子格子相互作用 / ダイナミクス

Outline of Annual Research Achievements

グラフェンやカーボンナノチューブなど、原子層からなる物質の超高速応答は、これらの物質の物性を理解するうえで必須の、非常に重要な物理的性質であるといえる。本研究ではこのような超高速応答を明らかにするために、サブ10fsの超短パルスレーザーを用いてポンププローブ実験を行い、光励起キャリア、及びコヒーレントフォノンのダイナミクスを明らかにした。特にカーボンナノチューブ系では、励起フォノンの位相や、緩和過程が光励起波長や、フェルミ面の位置によって大きく変化することを見出し、これらが、理論的も理解できることをモデル計算によって示した。以下ではその概要を説明する。
まず、コヒーレントフォノン実験では、プローブ光を波長分解することによって、どの共鳴状態において、フォノンが観測されるかを明らかにした。その結果、フォノンの振幅は、特異点間の共鳴励起が起こる波長で大きくなることを明らかにした。また、観測されるフォノンの位相が、偏光測定に用いる波長板によって大きく変化することを見出した。具体的には、分極の実部もしくは虚部を見ることによって、観測されるフォノンピークがダブルピークからシングルピークに変化することを明らかにした。また、各ピークの位相を観測すると、過去の理論計算の初期位相と一致する事から、波長分解コヒーレントフォノン分光法が、フォノンの位相測定に有効であることを示した。
さらに、カーボンナノチューブにおいて、バイアス電圧を印加することにより、フェルミ面を制御すると、励起状態の緩和過程が大きく変化することを見出した。この緩和過程は励起状態のキャリアと、ディラック電子とがクーロン相互作用により散乱されることで起こっている可能性があることを、理論的な計算を通して明らかにした。これらの結果は、原子層物質のキャリア緩和を理解するうえで重要である。

Research Progress Status

27年度が最終年度であるため、記入しない。

Strategy for Future Research Activity

27年度が最終年度であるため、記入しない。

Research Products

• [Journal Article] Terahertz Dielectric Response of Photoexcited Carriers in Si Revealed via Single-Shot Optical-Pump and Terahertz-Probe Spectroscopy (2015)
  • Author(s): Y. Minami, K. Horiuchi, K. Masuda, J. Takeda, and I. Katayama
  • Journal Title: Appl. Phys. Lett. Volume: 107 Issue: 17
  • DOI: 10.1063/1.4934697
  • NAID: 120005667737
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Terahertz-Induced Acceleration of Massive Dirac Electrons in Semimetal Bismuth (2015)
  • Author(s): Y. Minami, K. Araki, T. D. Dao, T. Nagao, M. Kitajima, J. Takeda, and I. Katayama
  • Journal Title: Sci. Rep. Volume: 5 Issue: 1
  • DOI: 10.1038/srep15870
  • NAID: 120006541921
  • Peer Reviewed
• [Journal Article] Real-Time Observation of Phonon-Polariton Dynamics in Ferroelectric LiNbO3 in Time-Frequency Space (2015)
  • Author(s): Y. Ikegaya, H. Sakaibara, Y. Minami, I. Katayama and J. Takeda
  • Journal Title: Appl. Phys. Lett. Volume: 107 Issue: 6 Pages: 062901-062901
  • DOI: 10.1063/1.4928480
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Ultrafast Time-Resolved Electron Diffraction Revealing the Nonthermal Dynamics of Near-UV Photoexcitation-Induced Amorphization in Ge2Sb2Te5 (2015)
  • Author(s): M. Hada, W. Oba, M. Kuwahara, I. Katayama, T. Saiki, J. Takeda, and K. G. Nakamura
  • Journal Title: Sci. Rep. Volume: 5 Issue: 1
  • DOI: 10.1038/srep13530
  • NAID: 120005667739
  • Peer Reviewed / Open Access
• [Journal Article] Time-Frequency Two-Dimensional Imaging Spectroscopy Using a Reflective Echelon Mirror (2015)
  • Author(s): J. Takeda, Y. Minami, and I. Katayama
  • Journal Title: Rev. Laser Eng. Volume: 43 Pages: 208-212
  • NAID: 130007957109
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] ナノカーボンのディラック電子＝フォノン間相互作用ダイナミクス (2015)
  • Author(s): 片山郁文、武田淳、北島正弘
  • Journal Title: 日本物理学会誌 Volume: 70 Pages: 770-775
  • Peer Reviewed
• [Journal Article] Terahertz-field-induced Nonlinear Electron Delocalization in Au Nanostructures (2015)
  • Author(s): K. Yoshioka, Y. Minami, K. Shudo, T. D. Dao, T. Nagao, M. Kitajima, J. Takeda, and I. Katayama
  • Journal Title: Nano Letters Volume: 15 Issue: 2 Pages: 1036-1040
  • DOI: 10.1021/nl503916t
  • NAID: 120005714807
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Journal Article] Resonant Enhancement of First- and Second-Order Coherent Phonons in Metallic Single-Walled Carbon Nanotubes (2014)
  • Author(s): K. Sato, K. Tahara, Y. Minami, I. Katayama, M. Kitajima, H. Kawai, K. Yanagi, and J. Takeda
  • Journal Title: Phys. Rev. B Volume: 90 Issue: 23 Pages: 235435-235435
  • DOI: 10.1103/physrevb.90.235435
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Nonlinear Electron Dynamics of Gold Ultrathin Films Induced by Intense Terahertz Waves (2014)
  • Author(s): Y. Minami, J. Takeda, T. D. Dao, T. Nagao, M. Kitajima, and I. Katayama
  • Journal Title: Appl. Phys. Lett. Volume: 105 Issue: 24
  • DOI: 10.1063/1.4904883
  • NAID: 120005549811
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Coherent Phonon and Surface-Enhanced Raman Scattering Dynamics in Solids (2014)
  • Author(s): J. Takeda, I. Katayama, K. Shudo and M. Kitajima
  • Journal Title: J. Lumin. Volume: 152 Pages: 23-27
  • DOI: 10.1016/j.jlumin.2014.01.058
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Ultrafast Crystalline-to-Amorphous Phase Transition in Ge2Sb2Te5 Chalcogenide Alloy Thin Film Using Single-Shot Imaging Spectroscopy (2014)
  • Author(s): J. Takeda, W. Oba, Y. Minami, T. Saiki and I. Katayama
  • Journal Title: Appl. Phys. Lett. Volume: 104 Issue: 26
  • DOI: 10.1063/1.4886969
  • NAID: 120005464758
  • Peer Reviewed / Acknowledgement Compliant
• [Presentation] Chirality Determination of Carbon Nanotube Solution Using Coherent Phonon Spectroscopy (2015)
  • Author(s): R-J. Xu, I. Katayama, Y. Minami, M. Kitajima, K. Yanagi, and J. Takeda
  • Organizer: The 16th International Conference on the Science and Application of Nanotubes
  • Place of Presentation: Nagoya, Japan
  • Year and Date: 2015-06-29
  • Int'l Joint Research
• [Presentation] Dynamics of Coherent Phonons in Metallic Single-walled Carbon Nanotubes (2015)
  • Author(s): I. Katayama, K. Maekawa, K. Sato, Y. Minami, K. Yanagi, M. Kitajima, and J. Takeda
  • Organizer: The 16th International Conference on the Science and Application of Nanotubes
  • Place of Presentation: Nagoya, Japan
  • Year and Date: 2015-06-29
  • Int'l Joint Research
• [Presentation] Electronic and Coherent-Phonon Resonances in Metallic Single-Walled Carbon Nanotubes (2015)
  • Author(s): I. Katayama, K. Sato, Y. Minami, M. Kitajima, K. Yanagi, and J. Takeda
  • Organizer: The 9th International Symposium on Ultrafast Surface Dynamics
  • Place of Presentation: Lake Biwa, Japan
  • Year and Date: 2015-05-25
  • Int'l Joint Research
• [Presentation] Long-lived Photoexcited Carriers in Si Revealed via THz Single-shot Spectroscopy (2015)
  • Author(s): Y. Minami, K. Masuda, K. Horiuchi, M. Kitajima, J. Takeda, and I. Katayama
  • Organizer: The 9th International Symposium on Ultrafast Surface Dynamics
  • Place of Presentation: Lake Biwa, Japan
  • Year and Date: 2015-05-25
  • Int'l Joint Research
• [Presentation] Ultrafast Expansion of Vibronic Modes in Alkanthiol Chain Adsorbed on Silver Nano-particles (2015)
  • Author(s): K. Shudo, N.Sugiyama, I.Katayama, M. Kitajima, and J. Takeda
  • Organizer: The 9th International Symposium on Ultrafast Surface Dynamics
  • Place of Presentation: Lake Biwa, Japan
  • Year and Date: 2015-05-25
  • Int'l Joint Research
• [Presentation] Terahertz Response of Long-lived Photoexcited Electrons in Silicon Observed Using Singleshot Terahertz Spectroscopy (2015)
  • Author(s): I. Katayama, K. Masuda, K. Horiuchi, Y. Minami, and J. Takeda
  • Organizer: The Conference on Lasers and Electro-Optics (CLEO 2015)
  • Place of Presentation: San Jose, USA
  • Year and Date: 2015-05-10
  • Int'l Joint Research
• [Presentation] Electron Dynamics in a Gold Thin Film Accelerated via an Intense Terahertz Field (2015)
  • Author(s): Y. Minami, T. D. Dao, T. Nagao, J. Takeda, M. Kitajima, and I. Katayama
  • Organizer: The Conference on Lasers and Electro-Optics (CLEO 2015)
  • Place of Presentation: San Jose, USA
  • Year and Date: 2015-05-10
  • Int'l Joint Research
• [Presentation] Broadband Single-Shot Spectroscopy Applicable to Photoinduced Nonlinear Dynamics (2015)
  • Author(s): J. Takeda, Y. Minami and I. Katayama
  • Organizer: Korea-Japan Joint Symposium on Semiconductor Physics and Nanophotonics
  • Place of Presentation: Daejeon, Korea
  • Year and Date: 2015-04-22
  • Int'l Joint Research
• [Presentation] Fermi Energy Dependence of High-Frequency Coherent Phonons in Metallic Carbon Nanotubes (2014)
  • Author(s): I. Katayama, K. Maekawa, K. Sat, Y. Minami, K. Yanagi, M. Kitajima and J. Takeda
  • Organizer: Internatinal Symposium on Computics: Quantum Simulation and Design (ISC-QSD2014)
  • Place of Presentation: Tokyo, Japan
  • Year and Date: 2014-12-01 – 2014-12-03
• [Presentation] Nonlinear Dynamics of Electrons on Dirac-Like Band in Semi-Metal Bismuth Induced by an THz Electric Pulse (2014)
  • Author(s): Y. Minami, K. Araki, T. D. Dao, T. Nagao, J. Takeda, M. Kitajima, and I. Katayama
  • Organizer: Internatinal Symposium on Computics: Quantum Simulation and Design (ISC-QSD2014)
  • Place of Presentation: Tokyo, Japan
  • Year and Date: 2014-12-01 – 2014-12-03
• [Presentation] Single-Shot Visualization of Ultrafast Amorphization in Chalcogenide Alloy Thin Films (2014)
  • Author(s): W. Oba, I. Katayama, Y. Minami, T. Saiki and J. Takeda
  • Organizer: Internatinal Symposium on Computics: Quantum Simulation and Design (ISC-QSD2014)
  • Place of Presentation: Tokyo, Japan
  • Year and Date: 2014-12-01 – 2014-12-03
• [Presentation] Nonlinear Response of Au Nanostructures Observed with Intense THz Pulses (2014)
  • Author(s): K. Yoshioka, Y. Minami, T. D. Dao, T. Nagao, K. Shudo, J. Takeda, M. Kitajima and I. Katayama
  • Organizer: 39th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz 2014)
  • Place of Presentation: Tucson, USA
  • Year and Date: 2014-09-14 – 2014-09-19
• [Presentation] Nonlinear Carrier Responses in Gold Thin Films Induced by Intense Terahertz Waves (2014)
  • Author(s): Y. Minami, T. D. Dao, T. Nagao, J. Takeda, M. Kitajima, and I. Katayama
  • Organizer: 19th International Conference on Ultrafast Phenomena
  • Place of Presentation: Okinawa, Japan
  • Year and Date: 2014-07-07 – 2014-07-11
• [Presentation] Electrochemical Control of Coherent Phonon Generations in Single-walled Metallic Carbon Nanotubes (2014)
  • Author(s): K. Maekawa, K. Sato, Y. Minami, I. Katayama, J. Takeda, K. Yanagi, M. Kitajima
  • Organizer: 19th International Conference on Ultrafast Phenomena
  • Place of Presentation: Okinawa, Japan
  • Year and Date: 2014-07-07 – 2014-07-11
• [Presentation] Single-shot Real-time Observation of Ultrafast Amorphization in Ge2Sb2Te5 Thin Film (2014)
  • Author(s): W. Oba, I. Katayama, Y. Minami, T. Saiki, and J. Takeda
  • Organizer: 19th International Conference on Ultrafast Phenomena
  • Place of Presentation: Okinawa, Japan
  • Year and Date: 2014-07-07 – 2014-07-11
• [Presentation] Nonlinear Carrier Dynamics in Semi-Metal Bismuth Induced by Intense Terahertz Field (2014)
  • Author(s): K. Araki, Y. Minami, T. D. Dao, T. Nagao, J. Takeda, M. Kitajima, and I. Katayama
  • Organizer: 19th International Conference on Ultrafast Phenomena
  • Place of Presentation: Okinawa, Japan
  • Year and Date: 2014-07-07 – 2014-07-11
• [Presentation] Carrier Dynamics of a Bismuth Thin Film Accelerated via Intense Terahertz Field (2014)
  • Author(s): Y. Minami, K. Araki, T. D. Dao, T. Nagao, J. Takeda, M. Kitajima, I. Katayama
  • Organizer: The Conference on Lasers and Electro-Optics (CLEO 2014)
  • Place of Presentation: San Jose, USA
  • Year and Date: 2014-06-08 – 2014-06-13
• [Presentation] Broadband Terahertz Generation Approaching Optical Communication Frequency Using Tilted DAST Crystals (2014)
  • Author(s): I. Katayama, M. Bito, E. Matsubara and M. Ashida
  • Organizer: The Conference on Lasers and Electro-Optics (CLEO 2014)
  • Place of Presentation: San Jose, USA
  • Year and Date: 2014-06-08 – 2014-06-13
• [Remarks] 武田・片山・南研究室HP
  • URL: http://www.ultrafast.ynu.ac.jp/index.html
• [Remarks] YNU研究拠点「光ナノ計測」
  • URL: http://www.laser-nanoscience.ynu.ac.jp/ja/