LATERAL SUPERLATTICES - MAGNETORESISTANCE, HALL-EFFECT AND COMMENSURATE ORBITS

The electron motion in a two-dimensional periodic potential and a perpendicular magnetic field, leads to interesting commensurability phenomena. Using nowadays micropatterning techniques, both weak (V0 << E(F)) and strong (V0 > E(F)) periodic potentials can be superimposed upon a two-dimensional electron gas. In the weak-modulation limit magnetoresistance oscillations periodic in 1/B reflect the commensurability between cyclotron orbit diameter 2R(c) and the superlattice period. A strong modulation acts predominantly as an array of periodic scatterers. The repulsive scattering potentials seem to trap electrons on commensurate orbits: the reduced carrier density manifests itself in peaks in the magnetoresistance, aperiodic in 1/B, and non-quantized plateaus in the Hall resistance.