Zeeman splittings of optical transitions at theLpoint of the Brillouin zone in semimagnetic semiconductors

Magnetoreflectivity measurements for optical transitions at the L point of the Brillouin zone have been performed on ${\mathrm{Zn}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{Mn}}_{\mathrm{x}}$Te and ${\mathrm{Hg}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{Mn}}_{\mathrm{x}}$Te alloys. Zeeman splittings of the transition labeled $E_1$ have been determined for both compounds. Furthermore, we have determined (for the first time in any semimagnetic semiconductor) Zeeman splittings of the $E_1$+${\Delta }_1$ transition in ${\mathrm{Hg}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{Mn}}_{\mathrm{x}}$Te. In ${\mathrm{Zn}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{Mn}}_{\mathrm{x}}$Te, as in previously studied ${\mathrm{Cd}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{Mn}}_{\mathrm{x}}$Te, it was necessary to introduce a variation of the ion-carrier exchange parameter with wave vectors in order to explain the data. The splitting of the $E_1$+${\Delta }_1$ feature in ${\mathrm{Hg}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{Mn}}_{\mathrm{x}}$Te has been found to have the opposite sign and the equal absolute value as the splitting of the $E_1$ feature, consistent with the prediction of Ginter et al. [Solid State Commun. 48, 849 (1983)].