Spectroscopic ellipsometry measurements of the complex dielectric
function of a series of Cd$_{0.63-y}$Mn$_{0.37}$Co$_y$Te single crystals grown by
the vertical Bridgman method have been performed in the 1.5 $\sim$ 5.5 eV
energy range at room temperat...
Spectroscopic ellipsometry measurements of the complex dielectric
function of a series of Cd$_{0.63-y}$Mn$_{0.37}$Co$_y$Te single crystals grown by
the vertical Bridgman method have been performed in the 1.5 $\sim$ 5.5 eV
energy range at room temperature. The measurement data were analyzed
by fitting the second-derivative spectra ($d^2 \varepsilon$/$d \omega^2$) with a
theoretical model, namely, the standard critical-point (SCP) line
shapes. The $E_1$, $E_1$+$\Delta_1$ and $E_2$ energies decreased with increasing Co
composition $y$, which is due to the hybridization effect of the
valence and conduction bands in Cd$_{1-x}$Mn$_x$Te with Co $3d$ levels.