  We study the ground states and low-energy excitations of a generic Dirac
material with spin-orbit coupling and a buckling structure in the presence of a
perpendicular magnetic field. The ground states can be classified into three
types under different conditions: SU(2), easy-plane, and Ising quantum Hall
ferromagnets. For the SU(2) and the easy-plane quantum Hall ferromagnets there
are goldstone modes in the collective excitations, while all the modes are
gapped in an Ising-type ground state. We compare the Ising quantum Hall
ferromagnet with that of bilayer graphene and present the domain wall solution
at finite temperatures. We then specify the phase transitions and transport
gaps in silicene in Landau levels 0 and 1. The phase diagram strongly depends
on the magnetic field and the dielectric constant. We note that there exists
triple points in the phase diagrams in Landau level N = 1 that could be
observed in experiments.
