Magnetoreflectivity study of the band structure of ${\mathrm{Hg}}_{1\mathrm{-}\mathrm{x}}$${\mathrm{Mn}}_{\mathrm{x}}$Te (0.026≤x≤0.106)

The reflectivity of semimagnetic ${\mathrm{Hg}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{Mn}}_{\mathrm{x}}$Te samples has been measured in magnetic fields up to 5 T at T=5 K for x=0.026, 0.035, 0.05, and 0.106. This range of compositions has not been previously investigated systematically by magneto-optical methods. Measurements in the far-infrared frequency range 30–400 ${\mathrm{cm}}^{\mathrm{-}1}$ were performed using Fourier-transform spectroscopy. The magnetization of two of the samples has also been measured. The magneto-optical transitions observed have been interpreted in terms of the modified Pidgeon-Brown model including exchange terms. Pinning effects were observed when the transition energies in Faraday and Voigt configurations became comparable with one of the longitudinal-optic-phonon energies.