  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.
