  Magnetism in carbon nanostructures is of high scientific interest, which
could lead to novel magnetic materials. The magnetic properties of symmetrical
and asymmetrical sized small fullerene dimers have been investigated using spin
polarized density functional theory. The interaction energies depict that small
fullerene cages form stable dimer structures and symmetrical sized fullerene
dimers are found more stable than asymmetrical sized dimers. The dimerization
of fullerene cages in different modes leads to change in their magnetic
properties. The non-magnetic fullerene cages become magnetic after formation of
dimer (C20-C20, C24-C24, C32-C32, C40-C40, C20-C24, C40-C44 and
C44-C50),whereas the magnetism of magnetic fullerenes is enhanced or lowered
after dimerization (C28-C28 C36-C36, C24-C28, C28-C32, C32-C36 and C36-C40).
The individual cages of dimer structures show ferromagnetic interactions
amongst them and resultant magnetic moment strongly depends on the type of
inter-connecting bonds. The magnetism may also be explained based on distortion
of carbon cages and change in the density of states (DOS) in dimer
configuration. The calculations presented show strong possibility of
experimental synthesis of small fullerene based magnetic dimers.
