Light-induced Ultrafast Phase Transformation Study using X-ray Free Electron Laser

A significant challenge in understanding the phase transformation of materials is whether one can identify and characterize the fine details of the complex ultrafast dynamics of molecules and materials. Many existing techniques only measure the initial and final states of the material transformations. The recent advance of X-ray free electron laser makes it possible to obtain critical information on the intermediate states or pathways during the phase transformation. In this talk, we show the recent results of a transition from a topological insulator to a standard insulator in Bi₂Se₃ followed by carrier-induced contraction and vibration modes and the crystalline-amorphous phase transformation of a phase change material as examples.<br/><br/>This research was supported by the National Research Foundation of Korea (NRF-2021R1A3B1077076).