1202.1362 (S. G. Sharapov et al.)

Anomalous growth of thermoelectric power in gapped graphene    [PDF]

S. G. Sharapov, A. A. Varlamov

There exist experiments indicating that at certain conditions like an
appropriate substrate a gap of the order of 10 meV can be opened at the Dirac
points of a quasi-particle spectrum of graphene. We demonstrate that opening of
such a gap can result in appearance of a fingerprint bump of the Seebeck signal
when the chemical potential approaches the gap edge. A magnitude of the bump
can be up to one order higher than already large value of the thermopower
occurring in graphene. Such a giant effect, accompanied by the non-monotonous
dependence on the chemical potential, is related to the emergence of a new
channel of quasi-particle scattering from impurities with the relaxation time
strongly dependent on the energy. We analyze behavior of conductivity and
thermopower in such system accounting for quasi-particle scattering from
impurities with the model potential in self-consistent scheme. Reproducing the
existing results for the case of gapless graphene we demonstrate a failure of
the simple Mott formula in the case under consideration.

View original: http://arxiv.org/abs/1202.1362