  We present a simple theory of thermoelectric transport in bilayer graphene
and report our results for the electrical resistivity, the thermal resistivity,
the Seebeck coefficient, and the Wiedemann-Franz ratio as functions of doping
density and temperature. In the absence of disorder, the thermal resistivity
tends to zero as the charge neutrality point is approached; the electric
resistivity jumps from zero to an intrinsic finite value, and the Seebeck
coefficient diverges in the same limit. Even though these results are similar
to those obtained for single-layer graphene, their derivation is considerably
more delicate. The singularities are removed by the inclusion of a small amount
of disorder, which leads to the appearance of a "window" of doping densities
$0<n<n_c$ (with $n_c$ tending to zero in the zero-disorder limit) in which the
Wiedemann-Franz law is severely violated.

Mesoscale and Nanoscale Physics