  It is demonstrated by means of density functional and ab-initio quantum
chemical calculations, that transition metal - carbon systems have the
potential to enhance the presently achievable area density of magnetic
recording by three orders of magnitude. As a model system, Co_2-benzene with a
diameter of 0.5 nm is investigated. It shows a magnetic anisotropy in the order
of 0.1 eV per molecule, large enough to store permanently one bit of
information at temperatures considerably larger than 4 K. A similar performance
can be expected, if cobalt dimers are deposited on graphene or on graphite. It
is suggested that the subnanometer bits can be written by simultaneous
application of a moderate magnetic and a strong electric field.
