Search for the Photo-Induced Hidden Phase in Inorganic and Organic Systems

Search for the Photo-Induced Hidden Phase in Inorganic and Organic Systems S. Koshiharaa,∗, K. Onda, Y. Okimoto and T. Ishikawa JST, CREST & Department of Materials Science, Tokyo Institute of Technology Meguro-ku Tokyo 152-8551, Japan Department of Environmental Chem. and Engineering, Tokyo Institute of Technology Nagatsuta-Yokohama, 226-8503, Japan We review the dynamical behavior of strongly electron–lattice (orbital) coupled system induced by photo-excitation of fs laser pulse. By virtue of the femtosecond (fs) spectroscopy and picosecond (ps) time-resolved X-ray diffraction measurements, we demonstrate that the photo-irradiation creates new ordered state so called as “hidden phase” which can never be realized under thermo-equilibrium condition. This exotic phase commonly plays the key role for realizing the gigantic photo-induced changes in optical properties of inorganic and organic electron–lattice strongly coupled systems.