  Spin-orbit coupling in graphene can be enhanced by chemical
functionalization, adatom decoration or proximity with a van der Waals
material. As it is expected that such enhancement gives rise to a sizeable spin
Hall effect, a spin-to-charge current conversion phenomenon of technological
relevance, it has sparked wide research interest. However, it has only been
measured in graphene/transition metal dichalcogenide van der Waals
heterostructures with limited scalability. Here, we experimentally demonstrate
spin Hall effect up to room temperature in bilayer graphene combined with a
nonmagnetic insulator, an evaporated bismuth oxide layer. The measured spin
Hall effect raises most likely from an extrinsic mechanism. With a large
spin-to-charge conversion efficiency, scalability, and ease of integration to
electronic devices, we show a promising material heterostructure suitable for
spin-based device applications.
