Electron localization and anisotropic magnetoconductivity in GaAs-AlAs superlattices

Abstract

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 $\ensuremath{\Delta}\ensuremath{\sigma}(B)$ 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 ${k}_{F}\ensuremath{\lambda}$ not much larger than unity such that weak localization theories cannot be strictly applied. We show that a self consistent model recently proposed by Bryksin and Kleinert accounts properly for the magnetoconductivity anisotropy.