Electronic properties and quantum Hall effect in multi-layer electron systems

We analyze the effect that the interaction between electrons has on the pro perties of a multi-layer electron system. We consider the case correspondin g to filling factor unity in each layer. In the case of an infinity superla ttice, the system presents ferromagnetic, canted antiferromagnetic or param agnetic interlayer spin correlations depending on the sample parameters. We have obtained that these three ground states are quantum Hall effect (QHE) phases, because of the existence of a finite activation energy. In the fer romagnetic phase the gap is due to the intrawell exchange energy, whereas i n the paramagnetic phase the gap appears due to the spatial modulation of t he interwell coherence. We have also studied the properties of multi-layer systems as a function of the number of electron sheets, N-L. We find that t he magnetic coupling of the electron layers depends strongly on the even/od d character of N-L. (C) 1998 Elsevier Science B.V. All rights reserved.