Dynamic Chirality at the Interface

Following a quick overview of the concept of chiral phonons and our experimental demonstration of strong phonon-spin coupling in rare-earth halides, I will present various optical approaches to control chiral phonons and study their ultrafast dynamics at the surface of bulk materials, in two-dimensional (2D) monolayers, and magnetic heterostructures. We found that the axial lifetime can span two orders of magnitude for phonon modes with different decoherence mechanisms. The induced magnetic effects can also drastically differ in magnitude and dynamics from what would be expected from the simple model of spin coupling with ionic current. Lastly, I will show evidence of chiral coupling across the van der Waals interface and tunable chirality at the chemically bonded interface. Our results call for further theoretical and experimental investigations into dynamic structure-property relationships and open promising avenues for on-demand modification of interfacial physics and chemistry.