Detecting Emergent Phases in Quantum Materials using High Harmonic Based Time and Angle Resolved Photoemission Spectroscopy*

Time and angle resolved photoemission spectroscopy (tr-ARPES) is a powerful tool to capture the band structure in 1D, 2D and topological materials with energy, momentum and time resolution. By gently exciting a quantum material with an ultrafast laser pulse and probing it with extreme ultraviolet high harmonic pulses, we measure not only the response times, but also see precisely how the electronic band structure changes. In combination, this makes it possible to identify the many body interactions underlying the ground state of quantum materials and thereby the nature of the pseudogap.[1]