Magnetoreflectance and magnetization of the Co-based wurtzite-structure diluted magnetic semiconductor Cd1-xCoxSe.

Abstract

Magnetoreflectance measurements of excitonic interband transitions in the wurtzite-structure compound ${\mathrm{Cd}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Co}}_{\mathit{x}}$Se with various directions of applied magnetic field combined with magnetization measurements, allowed us to determine the ion-carrier exchange parameters for the conduction and valence bands (${\mathit{N}}_{0}$\ensuremath{\alpha}=258\ifmmode\pm\else\textpm\fi{}10 meV, ${\mathit{N}}_{0}$\ensuremath{\beta}=-1883\ifmmode\pm\else\textpm\fi{}30 meV), without making any assumption concerning the band parameters. The magnitude of these exchange parameters, compared with the values previously obtained for ${\mathrm{Cd}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Fe}}_{\mathit{x}}$Se and ${\mathrm{Cd}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Mn}}_{\mathit{x}}$Se, indicates a small variation of the conduction-band exchange parameter, but an important enhancement of the valence-band exchange parameter. This large variation of the hybridization-induced exchange is explained within a generalized Schrieffer-Wolff formula.