  We report strongly enhanced perpendicular magnetic anisotropy (PMA) of Co
films by graphene coating from both first-principles and experiments. Our
calculations show that graphene can dramatically boost the surface anisotropy
of Co films up to twice the value of its pristine counterpart and can extend
the out-of-plane effective anisotropy up to unprecedented thickness of 25~\AA.
These findings are supported by our experiments on graphene coating on Co films
grown on Ir substrate. Furthermore, we report layer-resolved and
orbital-hybridization-resolved anisotropy analysis which help understanding the
physical mechanisms of PMA and more practically can help design structures with
giant PMA. As an example, we propose super-exchange stabilized Co-graphene
heterostructures with a robust out-of-plane constant effective PMA and linearly
increasing interfacial anisotropy as a function of film thickness. These
findings point towards possibilities to engineer graphene/ferromagnetic metal
heterostructures with giant magnetic anisotropy more than 20 times larger
compared to conventional multilayers, which constitutes a hallmark for future
graphene and traditional spintronic technologies.
