Interlayer magnetic coupling and the quantum Hall effect in multilayer electron systems

We study the effect that electron-electron interaction has on the properties of a multilayer electron system. We consider the case corresponding to filling factor unity in each layer and find that, as a function of the sample parameters, the system has ferromagnetic, canted antiferromagnetic, or paramagnetic interlayer spin correlations. These three ground states are QHE phases because of the existence of a finite activation energy. In the ferromagnetic phase the gap is due to the intrawell exchange energy, whereas in the paramagnetic phase the gap appears due to spatial modulation of the interwell coherence. [S0031-9007(98)07800-4].