 Rewriting the last expression as formula_43 it is clear that each Landau level contains as many states as in a 2DEG in a formula_44.Given the fact that electrons are fermions, for each state available in the Landau levels it corresponds two electrons, one electron with each value for the spin formula_45.However, if a large magnetic field is applied, the energies split into two levels due to the magnetic moment associated with the alignment of the spin with the magnetic field.