­Physics Colloquium - Award ceremony: Dresdner Promotionspreis Physik 2025

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Dr. Nilotpal Chakraborty: Magnon transport - A new window into topological quantum matter: I shall present a back-and-forth between theory and experiment on a novel magnon scattering setup in graphene quantum Hall heterojunctions, with the promise of developing a mesoscopic real-space probe for topology in quantum matter, especially quantum Hall insulators. The setup will be that of magnons scattering off a quantum Hall skyrmion crystal - a Wigner crystal of topological spin textures. First, I’ll discuss theory related to magnon emission and detection in such scattering setups and the magnon-skyrmion crystal interaction. Then, I’ll present experimental signatures which unveil the topological properties of such a crystal through non-equilibrium magnon-induced collective dynamics.

Dr. Maximilian Obst: Tailoring Phonon Polaritons in 2D van der Waal Materials: Tailoring the propagation of light at the nanometer-length scale is a major goal in nano-optics. Phonon polaritons - quasi-particles formed by light interacting with optical phonons - propagating in thin layers of van-der-Waals materials are key to solve this challenge, as they intrinsically offer high light confinement, low losses, and directional energy transport. Furthermore, they allow profound tuning of their properties, e.g. via changing the substrate or stacking multiple layers under defined twist angles. The work presented here focuses on the means of tailoring phonon polaritons at THz frequencies, an underexplored wavelength regime featuring the optical phonons of many materials.