Polaron-induced anti-Stokes photoluminescence under selective excitation in diluted magnetic semiconductors

Abstract

Anti-Stokes photoluminescence is observed under selective excitation in a bulk sample of the diluted magnetic semiconductor ${\mathrm{Cd}}_{1\ensuremath{-}x}{\mathrm{Mn}}_{x}\mathrm{Te}$ with $x$ $=$ 0.2. The anti-Stokes photoluminescence is induced by a two-step optical-absorption process that creates excitons via an alloy potential state and an impurity center. Both localized exciton magnetic polarons bound to the fluctuating alloy potential and exciton magnetic polarons bound to neutral acceptors participate in forming intermediate states with long lifetimes that cooperatively contribute to the anti-Stokes photoluminescence. The reabsorption of the anti-Stokes photoluminescence is also examined by considering the role of bound magnetic polarons. The localized Mn${}^{2+}$ spin ordering in magnetic polarons bound to the impurity center largely contributes in reducing reabsorption.