Exciton mixing and internal transitions of neutral magnetoexcitons in quantum wells

We present a theoretical investigation, in the effective-mass approximation, of exciton mixing and 1s - 2p(+/-) internal transitions of neutral magnetoexcitons in GaAs-Ga1-xAlxAs quantum wells. Theoretical results are obtained by diagonalizing the Kohn-Luttinger Hamiltonian in the presence of an external magnetic field along the growth direction of the quantum well, with mixing of appropriate light- and heavy-hole exciton states taken into account. We first perform the exciton calculations in the diagonal approximation, and take the exciton-envelope wave functions as linear combinations of products of hole and electron quantum-well states with Gaussian functions. Effects of exciton mixing are then calculated within perturbation theory. Theoretical results for the exciton internal transitions from 1s-like to 2p(+/-)-like magnetoexciton states in GaAs-Ga1-xAlxAs quantum wells, with well widths of 80 Angstrom, 100 Angstrom, 125 Angstrom, 150 Angstrom and 200 Angstrom, are found in overall agreement with optically detected resonance measurements. (C) 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.