Effect of a magnetic field on the photoluminescence from ${\mathrm{In}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As/GaAs and GaAs/${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As quantum wells

We have compared the predictions of a recently developed theory [G. Platero and M. Altarelli, Phys. Rev. B 39, 3758 (1989)] with experimental measurements, using a magnetic field oriented perpendicular to the growth axis, of the diamagnetic shift of light- and heavy-hole excitons as well as the effective light-hole g value in GaAs/${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As quantum wells and have found good agreement between theory and experiment. We also have measured the diamagnetic shift of the heavy-hole free exciton (HHFE) in narrow ${\mathrm{In}}_{0.1}$${\mathrm{Ga}}_{0.9}$As/GaAs single quantum wells with varying well size (${\mathit{L}}_{\mathit{z}}$=2, 4, 6, 10, and 17 monolayers) using the same magnetic-field orientation. The diamagnetic shift is observed to increase with decreasing well size and tends toward the value obtained for bulk GaAs for the narrowest well size investigated. We have also observed a spin splitting of the HHFE as well as the donor-bound exciton (${\mathit{D}}^0$,X) in the narrowest well size investigated. From the spin splitting we calculate an effective heavy-hole g value of 1.1±0.1, which is identical to the value observed for the heavy hole in bulk GaAs.