Transverse Magnetoresistance of GaAs/AlGaAs Heterojunctions in the Presence of Parallel Magnetic Fields

TL;DR

This paper models the resistivity of GaAs/AlGaAs heterojunctions under in-plane magnetic fields, revealing how Fermi contour distortion and impurity scattering cause positive magnetoresistance and anisotropic resistivity.

Contribution

It provides a semiclassical calculation of magnetoresistance considering Fermi contour distortion and impurity scattering, aligning well with experimental data.

Findings

Positive magnetoresistance depends on the perpendicular magnetic component.

Magnetoresistance magnitude correlates with residual impurity density.

Resistivity shows anisotropy related to carrier lifetime variations.

Abstract

We have calculated the resistivity of a GaAs\slash AlGaAs heterojunction in the presence of both an in--plane magnetic field and a weak perpendicular component using a semiclassical Boltzmann transport theory. These calculations take into account fully the distortion of the Fermi contour which is induced by the parallel magnetic field. The scattering of electrons is assumed to be due to remote ionized impurities. A positive magnetoresistance is found as a function of the perpendicular component, in good qualitative agreement with experimental observations. The main source of this effect is the strong variation of the electronic scattering rate around the Fermi contour which is associated with the variation in the mean distance of the electronic states from the remote impurities. The magnitude of the positive magnetoresistance is strongly correlated with the residual acceptor impurity density in the GaAs layer. The carrier lifetime anisotropy also leads to an observable anisotropy in the resistivity with respect to the angle between the current and the direction of the in--plane magnetic field.