Spin-flip Raman scattering studies of ZnSe/Zn_1-xMn_xSe multiple quantum well structures

Studies of electron spin-flip Raman scattering in a series of ZnSe/Zn_1-xMn_xSe heterostructures of different quantum well widths are reported. In all the specimens studied, a single spin-flip Raman band was observed with a Raman shift which showed the expected modified Brillouin function dependence on magnetic field and temperature. The dependence of the scattering intensity on the excitation energy shows strong resonant enhancement at energies corresponding to the quantum well exciton transitions, which, together with the selection rules, indicates that the spin-flip Raman signals arise from electrons localised in the ZnSe quantum wells. In our previous studies, the magnitude of the spin-flip Raman shift has been interpreted as a measure of the penetration of the electron envelope wavefunction into the barrier, leading to a simple means of determining the conduction band offset (including any contribution due to strain) of the system. However, in the present case, where the manganese concentration of the barrier is large and where the band offset is expected to be small, simple interpretation of the data in this way is not possible. Two effects in particular complicate the analysis of the data: the roughness of the heterointerface and the modified probability, compared to bulk material, of manganese antiferromagnetic spin-pairing at that interface. We use the results of recent theoretical work to show that the spin-flip Raman spectra are very sensitive to the state of the interface.