ULTrafast co-operative and coherent photo-switching of molecular MATErials – ULTiMATE

The opportunity to control the macroscopic state and then the physical properties (magnetic, optical, conduction') of a solid material on ultrafast time scales constitutes one of the new challenges and is the main target of this project. It is about the switching control of the macroscopic state of a material on ultrashort time-scales, corresponding to the ones of the molecular transformations observed in femtochemistry for molecules in solution. Very recent investigations have shown that a single laser pulse can drive the ferroelectric ordering of molecules, or generate a metallic state within one picosecond. Understanding and controlling the mechanism driving the cooperative switching in materials is of fundamental interest and will have some direct consequences for the future development of information processing and telecommunication. To accomplish these feat new ultrafast tools for watching directly the molecules move and transform (optical and X-ray diffraction techniques) as well as concepts (new kind of non linear dynamics and out of equilibrium physics) need to be developed. Our objective is clear: controlling, seeing, elucidating and designing such ultrafast co-operative processes in multi-stable molecular materials. This grant will provide the necessary springboard for our teams to develop and consolidate independent world-class research. It will give us a magnificent chance to design the cutting-edge experiments on revolutionary Xray-Free Electron Lasers, which will become available during the running of this project. The interaction between chemists and physicists developing complementary experiments will stimulate cross-fertilization and innovative development. It is clear that this project is an important key to maintain research activities in France around photoinduced phase transition at the world-class level. First of all, the development of time-resolved X-ray diffraction at Soleil will act as magnet to attract a larger community, limited in France at the present stage. Second development of time-resolved spectroscopy (optical, vibrational) will allow reaching ultra-short time resolution to detect elementary processes driving the transformation of matter. Finally, this work will allow a better understanding of the transformation of matter with light to design new materials. In addition, we will also design new ways to trigger photo-active materials through different ways of excitations: laser excitation wavelength (Vis-IR), polarisation, as well as excitation with trains of laser pulses.