Parallel Magnetic Field Induced Giant Magnetoresistance in Low Density Quasi-Two-Dimensional Layers

We provide a possible theoretical explanation for the recently observed giant positive magnetoresistance in high mobility low density quasi-two-dimensional electron and hole systems. Our explanation is based on the strong coupling of the parallel field to the orbital motion arising from the finite layer thickness and the large Fermi wavelength of the quasi-two-dimensional system at low carrier densities.