  Spin-flip Raman scattering of electrons and heavy-holes is studied for
resonant excitation of neutral and charged excitons in a
CdTe/Cd$_{0.63}$Mg$_{0.37}$Te quantum well. The spin-flip scattering is
characterized by its dependence on the incident and scattered light
polarization as well as on the magnetic field strength and orientation. Model
schemes of electric-dipole allowed spin-flip Raman processes in the exciton
complexes are compared to the experimental observations, from which we find
that lowering of the exciton symmetry, time of carrier spin relaxation, and
mixing between electron states and, respectively, light- and heavy-hole states
play an essential role in the scattering. At the exciton resonance, anisotropic
exchange interaction induces heavy-hole spin-flip scattering, while acoustic
phonon interaction is mainly responsible for the electron spin-flip. In
resonance with the positively and negatively charged excitons, anisotropic
electron-hole exchange as well as mixed electron states allow spin-flip
scattering. Variations in the resonant excitation energy and lattice
temperature demonstrate that localization of resident electrons and holes
controls the Raman process probability and is also responsible for symmetry
reduction. We show that the intensity of the electron spin-flip scattering is
strongly affected by the lifetime of the exciton complex and in tilted magnetic
fields by the angular dependence of the anisotropic electron-hole exchange
interaction.
