QUASI-PARTICLE EFFECTIVE MASS AND ENHANCED G-FACTOR FOR A 2-DIMENSIONAL ELECTRON-GAS AT INTERMEDIATE MAGNETIC-FIELDS

The single-particle self-energy in a Landau quantized two-dimensional electron gas has been evaluated in magnetic fields corresponding to arbitrarily large integer filling factors using the random-phase approximation. Quasiparticle energy separations have been determined for Landau levels near the Fermi level and comparisons are made with values determined from recent activation energy measurements on integral quantum Hall plateaus. Conclusions are drawn concerning the field strengths required for the validity of commonly adopted strong-field approximations. A series of transitions characterized by jumps in the spin polarization is predicted to occur near odd filling factors for sufficiently low densities.