Inelastic neutron scattering studies of II-VI diluted magnetic semiconductors (invited)

Abstract

Inelastic neutron scattering studies of AII1−xMxBVI diluted magnetic semiconductor (DMS) alloys with low and high concentations of the magnetic component (M) are reviewed. Measurements of inelastic scattering from isolated pairs of magnetic ions makes possible a direct determination of the ion–ion exchange parameters. This method has been used for JNN determination in Zn1−xMnxB (B=S, Se, Te) and Zn1−xCoxB DMS alloy families. Inelastic scattering experiments on DMS alloys with high magnetic ion concentrations (Zn1−xMnxTe and Cd1−xMnxTe with x=0.4–0.7) reveal that at low T the magnetic excitation spectra of these systems are dominated by magnonlike modes despite the absence of long-range magnetic order. A theoretical description of these excitations can be obtained using the numerical method developed by Ching and Huber. The model results reproduce remarkably well the dispersion and the line-shape characteristics of the excitation modes seen in the experiments.