  A new family of the low-buckled Dirac materials which includes silicene,
germanene, etc. is expected to possess a more complicated sequence of Landau
levels than in pristine graphene. Their energies depend, among other factors,
on the strength of the intrinsic spin-orbit (SO) and Rashba SO couplings and
can be tuned by an applied electric field $E_z$. We studied the influence of
the intrinsic Rashba SO term on the energies of Landau levels using both
analytical and numerical methods. The quantum magnetic oscillations of the
density of states are also investigated. A specific feature of the oscillations
is the presence of the beats with the frequency proportional to the field
$E_z$. The frequency of the beats becomes also dependent on the carrier
concentration when Rashba interaction is present allowing experimental
determination of its strength.
