PhD Proposal: Mathew Varghese

ADVISOR: Dr. Geoffrey Diederich

TITLE: Exciton Coupling to the Spin Ordering of van der Waals Magnetic Semiconductors

ABSTRACT: Van der Waals magnetic semiconductors provide a promising platform for coupling optical excitations to collective spin dynamics, with potential applications in energy-efficient information processing and quantum transduction. Chromium sulfur bromide (CrSBr) has emerged as an exciting platform for these studies because its strong coupling between excitons and magnetic order enables the optical detection of spin dynamics. However, the long-time evolution of its magnons and its microscopic interactions governing the excitonic states are not yet fully understood. This proposal investigates exciton coupling to the magnetic order in CrSBr through two complementary ultrafast optical experiments. Time-resolved pump-probe spectroscopy will be used to measure exciton-magnon coupling and magnon dynamics in both pristine flakes and engineered magnon cavities. Multidimensional coherent spectroscopy will be used to resolve interactions among the isolated excitonic states of CrSBr. Together, these studies will establish how information can be written, transferred, and detected in CrSBr and will provide a foundation for spintronic and magneto-optical devices.