KentuckyFC writes "The density of magnetic memory depends on the size of the magnetic domains used to store bits. The current state-of-the-art uses cobalt-based grains some 8nm across, each containing about 50,000 atoms. Materials scientists think they can shrink the grains to 15,000 atoms but any smaller than that and the crystal structure of the grains is lost. That's a problem because the cobalt has to be arranged in a hexagonal close packing structure to ensure the stability of its magnetic field. Otherwise the field can spontaneously reverse and the data is lost. Now a group of German physicists say they can trick a pair of cobalt atoms into thinking they are in a hexagonal close packing structure by bonding them to a hexagonal carbon ring such as graphene or benzene. That's handy because the magnetic field associated with cobalt dimers is calculated to be far more stable than the field in a cobalt grain. And graphene and benzene rings are only 0.5 nm across, a size that could allow an increase in memory density of three orders of magnitude."