MAGNETIC-FIELD-INDUCED RESONANT COUPLING BETWEEN 1S- AND 3D-EXCITON STATES

The giant Zeeman splitting of exciton states in semimagnetic semiconductors ${\mathrm{Cd}}_{1\ensuremath{-}x}{\mathrm{Mn}}_{x}\mathrm{Te}$ and ${\mathrm{Cd}}_{1\ensuremath{-}x}{\mathrm{Co}}_{x}\mathrm{Te}$ has been exploited to study the coupling of originally ground $(1s)$ and excited $(3d)$ exciton states. At a certain magnetic field the upper Zeeman pattern of the $1s$ state passes through the lower pattern of the $3s$ state, giving to the latter half of its oscillator strength. Such an anticrossing behavior has been observed in circularly polarized magnetoreflection spectra, which allowed a determination of exchange coupling constants in the studied materials.