Multiple spin-flip Raman scattering in CdSe/ZnMnSe quantum dots
Multiple Mn2+ spin-flip Raman scattering (SFRS) in Voigt geometry was observed in self-organized disk-shaped quantum dots (QDs) of CdSe/Zn0.99Mn0.01Se, where magnetic ions and QD carriers are spatially separated and therefore the exchange interaction between them is expected to be weak. Many lines (about ten) were observed in SFRS spectra, yet the overlapping of the hole wave function with Mn2+ ions is very small, in agreement with both the absence of observable Zeeman splitting of the photoluminescence line and the calculation. Interesting polarization properties of SFRS spectra were observed which could be affected by tilting the sample out of normal alignment and changing the temperature. These polarization properties were attributed to the selection rules in SFRS in Voigt geometry. It has been found that the theoretical model suggested by Stühler et al. [J. Cryst. Growth 159, 1001 (1996)] does not describe the SFRS spectra in systems with weak exchange interaction between charge carriers and magnetic ions. A qualitative model is suggested here for description of SFRS in such systems.