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Abstract:
We report an investigation into the magnetic and electronic properties
of partially hydrogenated vertically aligned few layers graphene (FLG)
synthesized by microwave plasma enhanced chemical vapor deposition. The
FLG samples are hydrogenated at different substrate temperatures to
alter the degree of hydrogenation and their depth profile. The unique
morphology of the structure gives rise to a unique geometry in which
graphane/graphone is supported by graphene layers in the bulk, which is
very different from other widely studied structures such as
one-dimensional nanoribbons. Synchrotron based x-ray absorption fine
structure spectroscopy measurements have been used to investigate the
electronic structure and the underlying hydrogenation mechanism
responsible for the magnetic properties. While ferromagnetic
interactions seem to be predominant, the presence of antiferromagnetic
interaction was also observed. Free spins available via the conversion
of sp(2) to sp(3) hybridized structures, and the possibility of unpaired
electrons from defects induced upon hydrogenation are thought to be
likely mechanisms for the observed ferromagnetic orders.
