Interband magneto-optics in GaAs/AlGaAs quantum wells in a parallel field

Abstract

We present a theoretical and experimental study of interband magneto-optics in GaAs/AlGaAs quantum wells (QW's) in the presence of a magnetic field applied in the plane of the barriers. In this configuration both electrons and holes experience a diamagnetic shift and a spin splitting of the levels. The mixture of the heavy and light character for the hole subbands depends on the competition between the magnetic and the confinement potentials, i.e., on the ratio between the magnetic length and the well width. For thin wells confinement effects dominate over the effect of the magnetic field. In this case, the heavy-hole splitting is almost negligible. On the contrary, the light-hole splitting can be shown to depend only on the hole effective magnetic moment κ, the parameter introduced by Luttinger in analogy to the effective magnetic moment g ∗ of electrons. Therefore a measure of such splitting yields directly a determination of this parameter which is not easy to obtain from measurements of the bulk or of quantum wells in a perpendicular field where the observable quantities are mainly determined by the hole band parameters γ 1, γ 2, γ 3. From a comparison between theory and experiments we obtain a value of κ = 0.7 for GaAs which is smaller than the value commonly assumed in the literature.