Geometrical resonance in the resistivity of wide quantum wells

We studied size-effects in wide parabolic quantum wells by measuring the low field magnetoresistance in perpendicular and parallel magnetic field configurations. We have also studied the evolutions of the resistivity oscillations as a function of the electron sheet density NS, by in situ illumination of the samples at the temperature of View the MathML source. We observed the maximum in the resistivity in the perpendicular magnetic field when the cyclotron radius was equal to the width of the electronic slab Rc=We. It allows to determine the width We as a function of the electron density. The oscillation amplitude decreases with NS, which can be attributed to the increase of the probability of electrons to be specularly reflected by the boundary with increase of the electron slab width. In parallel magnetic field we also found oscillations corresponding to Rc≈We and Rc/We≈2.2 in agreement with quantum-mechanical calculations of the size effects in narrow quantum wires.