Zeeman splitting of exciton and magnetization in ${\mathrm{Cd}}_{1\mathrm{-}\mathrm{x}}$${\mathrm{Mn}}_{\mathrm{x}}$Te: Anomalous behavior at high x

Magnetoreflectivity measurements were performed in order to determine the exciton splitting in ${\mathrm{Cd}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{Mn}}_{\mathrm{x}}$Te (0.09≤x≤0.73) at helium temperature and in applied fields up to 5.5 T. Magnetization measurements were carried out on the same samples under the same conditions. Comparison yields the splitting ΔE as a function of the average spin component ‖x〈$S_z$〉‖ for different values of x. The corresponding curves are found to be roughly linear, but the slope is drastically reduced at high x values. This anomalous behavior, observed previously in ${\mathrm{Zn}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{Mn}}_{\mathrm{x}}$Te, is explained in terms of a second-order perturbation calculation of the valence- and conduction-band splittings.