Vertical longitudinal magnetoresistance of semiconductor superlattices

Vertical longitudinal magnetoresistance (VLMR) caused by the peculiar shape of the Fermi surface of a superlattice has been observed in GaAs/AlxGa1-xAs superlattices. This VLMR occurs when the electrons occupy the open Fermi surface and their motion in the plane of the layers is quantized by a magnetic field. It was shown that there exists a critical magnetic field that cancels the contribution of the electrons occupying the open Fermi surface to the vertical conductivity in the case when the chemical potential exceeds the width of the miniband, thus resulting in the observed VLMR. This effect produces the conditions necessary to observe the quantized Hall effect in the three-dimensional electron system of a superlattice.