Resonant electron spin-flip Raman scattering in CdTe and the diluted magnetic semiconductorCd1−xVxTe

Abstract

Resonant enhancement enables the discovery and delineation of spin-flip Raman scattering (SFRS) from free or donor-bound electrons in diluted magnetic semiconductors containing $3d$ transition-metal ions at doping concentrations. In such studies, the intrinsic g factor of the host, CdTe in the present case, has to be accounted for accurately. The SFRS in CdTe yields the conduction band electron g factor of $\ensuremath{-}1.676\ifmmode\pm\else\textpm\fi{}0.007$ and displays two resonance peaks mediated by free and donor-bound excitons, respectively. Excitonic signature in modulated reflectivity signals the successful formation of ${\mathrm{Cd}}_{1\ensuremath{-}x}{\mathrm{V}}_{x}\mathrm{Te}$ as an alloy, whereas magnetization measurements show vanadium ions incorporated as ${\mathrm{V}}^{2+}$ with $x\ensuremath{\sim}4\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}.$ SFRS of ${\mathrm{Cd}}_{1\ensuremath{-}x}{\mathrm{V}}_{x}\mathrm{Te}$ displays vanadium related SFRS shifts of a sign opposite to that of the host. This indicates a ferromagnetic $s\ensuremath{-}d$ exchange interaction between the s-like conduction electrons and the $3d$ shell of ${\mathrm{V}}^{2+}$ in ${\mathrm{Cd}}_{1\ensuremath{-}x}{\mathrm{V}}_{x}\mathrm{Te};$ from the linear dependence of the $s\ensuremath{-}d$ exchange energy as a function of magnetization $\ensuremath{\alpha}{N}_{0},$ the $s\ensuremath{-}d$ exchange constant is deduced to be $285\ifmmode\pm\else\textpm\fi{}8\mathrm{meV}.$