Seminar：Multiple mobile excitons manifested as sidebands in ARPES

Excitons are bound states between electrons and holes, whose charge neutrality and a priori itinerant nature make them interesting as potential transmitters of information. However, the demonstration of the mobility of such composite excitations has remained inaccessible to traditional optical experiments which only create and detect excitons with negligible momentum or group velocity. Here, we use angle-resolved photoemission spectroscopy (ARPES) to detect dispersing excitons in the quasi-one dimensional metallic trichalcogenide TaSe3. While screening usually suppresses exciton formation in metals, the low density of conduction electrons, the low dimensionality, and two many-body effects favor them. In this presentation I will introduce the idea how to use ARPES to detect dispersing excitons in the quasi-one-dimensional metallic trichalcogenide. We show that the interplay of dilute conduction electrons, low effective dimensionality, and heavy quasiparticles seems to result not only in a single excitonic branch of excitations, but even in multiple “sidebands”, suggesting the possibility of creating bound states with different internal structure.