Electron localization and anisotropic magnetoconductivity in GaAs-AlAs superlattices

We have performed magnetoresistance measurements in two GaAs-AlAs superlattices at low magnetic fields and various B-field orientations. Due to the multilayer structure of the samples, the magnetic correction Delta sigma(B) to the conductivity depends on the magnetic field orientation and is largest when B is perpendicular to the layers. It decreases slightly in the wide miniband superlattice [quasi-three-dimensional (3D) system] whereas it decreases strongly in the narrow miniband superlattice (quasi-2D system) when the magnetic field is tilted. In fact, these microstructures show k(F)lambda not much larger than unity such that weak localization theories cannot he strictly applied. We show that a self consistent model recently proposed by Bryksin and Kleinert accounts properly For the magnetoconductivity anisotropy. [S0163-1829(99)00723-7].