Detecting electron-phonon coupling during photoinduced phase transition

Photoinduced phase transitions have been intensively studied owing to their promising potential for next-generation devices. Here, the authors develop a novel analysis method: the so-called frequency-domain ARPES (FDARPES). They extend a well established measurement method of time-domain ARPES to detect how electrons are interacting with phonons during the photoinduced insulator-to-metal transition for Ta${}_{2}$NiSe${}_{5}$. They successfully unravel the underlying nature of the photoinduced phase transition. This method has general applicability to other photoinduced phase transitions, including photoinduced magnetism or superconductivity.