Magnetization of quantum Hall systems

The magnetic properties of a two-dimensional interacting electron system in a strong magnetic field are considered in the quantum Hall regime, where the motion of the electrons is restricted to the lowest Landau level. We apply an approach based on the many-particle quantum-field theory which we developed recently for the spin-polarized system in the fractional quantum Hall regime, and which treats the problem of the degeneracy of a partially filled Landau level properly. Via a gauge transformation of the fermion Green's function, we achieve a dressing of the propagator with multiple collective excitations. Our theory allows a calculation of the magnetic polarization M(T) for higher temperatures T, where M(T)less than or similar to 0.4 is not too large. For filling factor nu=1 we obtain a magnetic polarization M(T) which agrees quite well with the data of a NR?IR experiment by Barrett [Phys. Rev. Lett. 74, 5112 (1995)].