Magnetic-ion-pair interaction in (Cd,Mn)Te and (Cd,Mn)Se using spin-flip Raman scattering and magnetization

Abstract

Isolated Mn ion pairs in dilute magnetic semiconductors exhibit steplike increases in the total spin alignment with increasing magnetic field. These steps in ${\mathrm{Cd}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$${\mathrm{Mn}}_{\mathrm{x}}$Te and ${\mathrm{Cd}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$${\mathrm{Mn}}_{\mathrm{x}}$Se, with x\ensuremath{\le}0.05, are studied using spin-flip Raman scattering and magnetization measurements at 0.5\ensuremath{\le}T\ensuremath{\le}1.3 K. In dc fields to 30 T the optical spectra show three steps for (Cd,Mn)Te and two for (Cd,Mn)Se. Analysis of the field positions of the steps obtained by both methods gives the nearest-neighbor exchange constant ${J}_{\mathrm{NN}/{k}_{B}=\mathrm{\ensuremath{-}}6.1\ifmmode\pm\else\textpm\fi{}0.2}$ K for the telluride and -7.7\ifmmode\pm\else\textpm\fi{}0.3 K for the selenide. By comparison of the optical and magnetization results, the s-d exchange parameter for (Cd,Mn)Te is found to be \ensuremath{\alpha}${N}_{0}$=211\ifmmode\pm\else\textpm\fi{}10 meV.