Measuring the Zeeman energy and the spin polarization of a 2DEG in quantum wells

We compare Raman scattering (RS) and photoluminescence (PL) measurements on a spin-polarized two-dimensional electron gases (2DEG) in Cd1−xMnx Te quantum wells in an applied magnetic field. RS spectra, for zero wave vector, show the collective spin–flip excitation corresponding to the Zeeman energy Z and the single electron spin–flip energy Z*. The Voigt magneto-PL spectra show conduction band splitting, which matches Z rather than Z*, indicating that the PL spectra are influenced by collective effects. Differences in the spin polarization values for large electron densities are also observed and attributed to the renormalization of mass due to Coulomb interactions.