Photoinduced coherent acoustic phonon dynamics inside Mott insulator Sr2IrO4 films observed by femtosecond X-ray pulses

摘要: We investigate the transient photoexcited lattice dynamics in a layered perovskite Mott insulator Sr2IrO4 film by femtosecond X-ray diffraction using laser plasma-based source. The ultrafast structural of thin films are determined observing shift and broadening (0012) Bragg after excitation 1.5 eV 3.0 eV pump photons for with different thicknesses. observed response can be well interpreted as distinct three-step due to propagation coherent acoustic phonons generated photoinduced quasiparticles (QPs). Employing normalized phonon model, we found that angular shifts peak collapse into universal curve introducing coordinates account thicknesses photon energies, pinpointing origin distortion its early evolution. In addition, photocurrent measurement indicates QPs charge neutral excitons. Mapping correlating QP (UXRD) establish powerful way study electron-phonon coupling uncover exotic physics strongly correlated systems under nonequilibrium conditions.We ar...