Motivated by very recent studies of Coulomb drag in grahene-BN-graphene
system we develop a theory of Coulomb drag for the Fermi liquid regime, for the
case when the ratio of spacer thickness d to the Fermi wavelength of
electrons is arbitrary. The concentration (n) and thickness dependence of the
drag resistivity is changed from nβ3dβ4 for the thick spacer to
nβ1β£ln(nd2)β£ for the thin one.Comment: final version; more details on the solution of electrostatic problem
and some references are adde