Magnetoreflection and magnetophotoluminescence in the dilute magnetic semiconductor Zn1−xMnxTe

Abstract

Magnetoreflection (MR) and magnetophotoluminescence (MPL) are studied in the diluted magnetic semiconductor ${\mathrm{Zn}}_{1\ensuremath{-}x}{\mathrm{Mn}}_{x}\mathrm{Te}$. The use of both methods in parallel allows us to follow features resulting from the mean-field exchange behavior as well as individual characteristics of ${\mathrm{Mn}}^{2+}$ paramagnetic ions. Resonance linewidths observed in MR are analyzed and shown to depend on spin-dependent scattering of excitons. A striking feature of the MPL spectrum is an enhancement of all spin-polarized luminescence structures in an external magnetic field. Relations between the Zeeman energy shift of exciton transitions due to exchange interaction of Mn ions with mobile carriers and circular polarization of MPL due to internal recombination in ${\mathrm{Mn}}^{2+}$ are revealed. Mixing of left and right circular light polarizations is demonstrated in excitonic and donor-acceptor pair (DAP) structures of MPL peaks. An enhancement of binding energy with increasing magnetic field for excitons localized by potential fluctuations is demonstrated and explained. It is observed that the energy of MPL peaks related to DAPs is only weakly sensitive to magnetic field. This relative stability is caused by a suppression of the mean-field Zeeman shift due to the two-component form of impurity wave functions. The simultaneous presence of paramagnetic ions and residual nonmagnetic impurities in our ${\mathrm{Zn}}_{1\ensuremath{-}x}{\mathrm{Mn}}_{x}\mathrm{Te}$ samples provides for a rich physical picture.