Separated Electron-Phonon and Phonon-Phonon Scatterings Across Interface in Thin Film LaCoO /SrTiO.

Electron-phonon coupling (EPC) and phonon-phonon scattering (PPS) are at the core of the microscopic physics mechanisms of vast quantum materials. However, to date, there are rarely reports that these two processes can be spatially separated, although they are usually temporally detached with different characteristic lifetimes. Here, by employing ultrafast spectroscopy to investigate the photo-carrier ultrafast dynamics in a LaCoO thin film on a (100) SrTiO substrate, intriguing evidence is found that the two interactions are indeed spatially separated.