  The research field of spintronics has sought, over the past 25 years and
through several materials science tracks, a source of highly spin-polarized
current at room temperature. Organic spinterfaces, which consist in an
interface between a ferromagnetic metal and a molecule, represent the most
promising track as demonstrated for a handful of interface candidates. How
general is this effect? We deploy topographical and spectroscopic techniques to
show that a strongly spin-polarized interface arises already between
ferromagnetic cobalt and mere carbon atoms. Scanning tunneling microscopy and
spectroscopy show how a dense semiconducting carbon film with a low band gap of
about 0.4 eV is formed atop the metallic interface. Spin-resolved photoemission
spectroscopy reveals a high degree of spin polarization at room temperature of
carbon-induced interface states at the Fermi energy. From both our previous
study of cobalt/phthalocyanine spinterfaces and present x-ray photoemission
spectroscopy studies of the cobalt/carbon interface, we infer that these highly
spin-polarized interface states arise mainly from sp2-bonded carbon atoms. We
thus demonstrate the molecule-agnostic, generic nature of the spinterface
formation.
