Anisotropy of spin g factor in GaAs/Ga1-xAlxAs symmetric quantum wells

Five-level k center dot p band model is used to describe the spin g factor of conduction electrons in undoped GaAs/Ga0.65Al0.35As quantum wells (QWs) with an external magnetic field parallel and transverse to the growth direction [001]. Far-band corrections to the model are also included in the theory. It is found that for QWs narrower than 10 nm the transverse g(perpendicular to) factor is slightly higher than the parallel one g(parallel to). Our theory without any adjustable parameters describes very well the existing experimental data of various authors for both field configurations and well widths 3 nm <= d <= 25 nm. Comparison between the theory and experiment probes the validity of the k center dot p approach for lengths of few lattice periods.