  The demand for compact, high-speed and energy-saving circuitry urges higher
efficiency of spintronic devices that can offer a viable alternative for the
current electronics. The route towards this goal suggests implementing
two-dimensional (2D) materials that provide large spin polarization of charge
current together with the long-distance transfer of the spin information. Here,
for the first time, we experimentally demonstrate a large spin polarization of
the graphene conductivity ($\approx 14\%$) arising from a strong induced
exchange interaction in proximity to a 2D layered antiferromagnetic. The strong
coupling of charge and spin currents in graphene with high efficiency of spin
current generation, comparable to that of metallic ferromagnets, together with
the observation of spin-dependent Seebeck and anomalous Hall effects, all
consistently confirm the magnetic nature of graphene. The high sensitivity of
spin transport in graphene to the magnetization of the outermost layer of the
adjacent interlayer antiferromagnet, also provides a tool to read out a single
magnetic sub-lattice. The first time observations of the electrical and thermal
generation of spin currents by magnetic graphene suggest it as the ultimate
building block for ultra-thin magnetic memory and sensory devices, combining
gate tunable spin-dependent conductivity, long-distance spin transport and
spin-orbit coupling all in a single 2D material.
