Ultrafast interlayer dynamics in graphene-based van-der Waals heterostructures

The continued drive toward smaller, faster, and more energy-efficient electronic devices demands a microscopic understanding of how charge carriers and band structures evolve on ultrafast timescales. In particular, novel quantum materials - whose properties are governed by strong electronic correlations - offer new opportunities for functionality beyond conventional semiconductors, provided their nonequilibrium behavior can be controlled and understood. In this talk, I will demonstrate how time- and angle-resolved photoemission spectroscopy (trARPES) serves as a powerful ultrafast probe of carrier dynamics and transient band structures. I will present three representative case studies. First, I will discuss ultrafast charge transfer in van-der-Waals heterostructures, where efficient light absorption via excitons is followed by rapid charge separation relevant for light harvesting and detection [1,2]. Second, I will show how the presence of a proximity-coupled 2D metal affects the non-equilibrium carrier dynamics of graphene [3]. Finally, I will present evidence for hybridization between highly itinerant Dirac electrons and strongly localized flat-band states, indicating the emergence of hybrid quasiparticles with possibly exotic properties.

References:

[1] Sci. Adv. 6, eaay0761 (2020)

[2] Phys. Rev. Lett. 127, 276401 (2021)

[3] Phys. Rev. B 111, 125158 (2025)