Photoexcited spin states in diluted magnetic semiconductor quantum structures

Exciton photoluminescence in a diluted magnetic asymmetric quantum well has given clear evidence of "asymmetric exciton magnetic polaron states" in magnetic fields. The theoretical calculation to interpret the observed magneto-optical data has clarified the importance of exciton localization associated with the interface disorder and the alloy potential fluctuation in addition to the exciton magnetic polaron formation in the asymmetric diluted magnetic barrier. The possibility of a "bifurcated" exciton states is discussed. The transient four-wave-mixing nonlinear spin selective optical measurements revealed the spin-structure of excitons and biexcitons in diluted magnetic quantum structures. The effects of the magnetic field on biexciton states have been investigated. The photoluminescence transition from the biexciton to exciton states has been investigated in magnetic fields, and the stability of the biexciton states in either bonding (spin singlet) or anti-bonding states (spin triplet) is discussed. We have proposed methods to deduce the interface magnetism in the diluted magnetic quantum structures from the high-field Zeeman splitting of exciton photoluminescence up to 60 T. (C) 2001 Elsevier Science B.V. All rights reserved.