CLASSICAL AND QUANTUM MOTION IN LATERAL SUPERLATTICES

We have studied the magnetoresistance of a two-dimensional electron gas (2DEG) subjected to a periodic potential created using electrostatic gates. Periods vary between 100 nm and 500 nm. The detailed behaviour of the magnetoresistance, which includes a positive contribution at very low magnetic fields and oscillatory behaviour periodic in 1/B at higher fields, is explained successfully within a semi-classical framework. The dependence of the magnetoresistance on amplitude of potential and temperature is explained quantitatively. The limits to the validity of the semi-classical approach are derived. By rotating the sample we are able to alter the magnetoresistance in an anisotropic fashion depending on the relative direction between the equi-potentials and the axis of rotation. This is interpreted in terms of the in-plane magnetic field allowing the zero-point motion in the confinement direction to be observed in the plane of the 2DEG.