Realization of room-temperature ferromagnetic semiconducting state in graphene monolayer

Room-temperature ferromagnetic semiconductor is vital in nonvolatile digital circuits and it can provide an idea system where we can make use of both charge and spin of electrons. However, seeking room-temperature ferromagnetic semiconductors is still just an appealing idea that has never been realized in practice up to now. Here we demonstrate that graphene monolayer, hybridized with underlying Ni(111) substrate, is the room-temperature ferromagnetic semiconductor that has been continuously searched for decades. Our spin-polarized scanning tunnelling microscopy (STM) experiments, complemented by first-principles calculations, demonstrate explicitly that the interaction between graphene and the Ni substrate generates a large gap in graphene and simultaneously leads to a relatively shift between majority- and minority-spin bands. Consequently, the graphene sheet on the Ni substrate exhibits a spin-polarized gap with energy of several tens meV even at room-temperature. This result makes the science and applications of room-temperature ferromagnetic semiconductors achievable and raises hopes of graphene-based novel information technologies.