Different Time Characteristics of Conduction and Valence Bands in a Photo-Excited Excitonic Insulator

Photoinduced electronic state changes in the excitonic insulator Ta2Ni0.9Co0.1Se5 were investigated using transient photoemission spectroscopy. The results revealed that the conduction and valence bands exhibit different temporal changes during the photoinduced melting of the exciton condensed state.