Topological Excitonic States and Their Fingerprints on Electronic Structure

Time and angle resolved photoemission spectroscopy has been recently shown to be a powerful tool to reveal exciton formation in the single particle spectral function, opening the exciting frontier to study momentum dependent exciton driven band structure renormalization, and ultimately search distinctive signature of exciton condensation in the band structure. Here I will discuss our recent work utilizing XUV and UV time resolved ARPES to study exciton formation in real time and across the exciton Mott transition. I will show how their formation can uniquely modify the band structure in a k dependent way and will reveal under which conditions these excitonic state can be driven in the presence of topological invariants, what properties of the topological state persists and what are their fingerprints in the material’s band structure. I will also discuss the potential of these materials to drive excitonic condensation.