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The036th KARC Colloquium

The036th KARC Colloquium was ended. Thank you for the participation.


Date&Time Tuesday May 18, 2004 15:00-16:30
Place Conference room, 2F. Laboratory Bldg. No. 1, KARC
Lecturer “Ultra fast photo-induced phase transition in organic CT crystals probed by time-resolved X-ray measurement”
Speaker Prof. Shin-ya Koshihara
Department of Materials Science, Tokyo Institute of Technology
Abstract It is an attractive target for material science to find a system which shows the cooperative response triggered by external stimulation of light. The purpose of our study is to report experimental evidences indicating that the photo-injected local excitation can really trigger the cooperative multi-electron transfer resulting in macroscopic lattice order in correlated dielectric materials by virtue of the electron-electron and electron-lattice interactions. In this sense, this unique photo-induced effect can be named as photo-induced phase transition (PIPT).
Here, we mainly focus on the dynamics of the photo-induced cooperative charge transfer, so called as photo-induced neutral-ionic phase transition, in organic charge transfer crystal tetrathiafulvalene(TTF)-chloranil(CA)[1]. In this system, nonlinear response to light excitation such as threshold-like behavior has been observed [1]. We will also report the recent development in the study of photo-induced ferroelectric order accompanied with the dramatic change in nonlinear optical property utilizing the SOR system combined with fs-Laser [2,3]. In addition, we want to briefly show the dynamical behavior of ultra-fast photo-switching between Insulator (CO) - Metal phases in EDO based crystals at room temperature. Obtained results clearly indicate that 1/4 filled systems are important not only for the study of exotic superconductivity but also for non-equilibrium materials science and application.
  1. [1] S.Koshihara et.al. J. Phys. Chem, B 103, 2592 (1999)
    　　(FEATURE ARTICLES).
  2. [2] T.Luty et.al. Europhys. Lett. 59, 619 (2002).
  3. [3] E.Collet et.al. Science 300, 612 (2003).
Language Japanese
Admission Free
Organizer Shingo SAITO Ph.D.
Advanced Laser Technology Group, Kansai Advanced Research CenterNational Institute of Information and Communications Technology