Probing spin dynamics in InSe with time-resolve Kerr rotation*

The layered structure of two-dimensional materials can allow for enhanced flexibility and control optical, electrical, and spin properties in devices. Currently, transition metal dichalcogenides are the canonical example of such control, but methods of spin manipulation in these materials are often limited by spin-valley locking, which couples carrier spin projection with momentum. This prevents the level of spin control possible in traditional, direct band gap, III-V semiconductors, motivaitng a search for other potential van der Waals materials for spintronics. InSe, a group-III monochalcogenide, has been predicted to have direct bandgap, spin-dependent optical selection rules, thus avoiding spin-valley locking. Here, we present measurements of optical spin orientation, relaxation, and precession in InSe using time-resolved Kerr rotation in the near infrared spectrum. These observations demonstrate the unexplored potential of a diverse set of van der Waals materials for spintronics.