Raman scattering by phonons and magnons in semimagnetic semiconductors:Cd1−xMnxTe

Abstract

${\mathrm{Cd}}_{1\ensuremath{-}x}{\mathrm{Mn}}_{x}$ Te alloys possess a homogeneous crystal phase having a zinc-blende structure for $0\ensuremath{\le}x\ensuremath{\le}0.7$. Their Raman spectra exhibit two pairs of sharp lines characteristic of the zone center "CdTe-like" and "MnTe-like" LO-TO modes. Some quasicontinuous features in the Raman spectrum can be traced to first-order processes which become allowed as a result of the absence of strict translational symmetry and reflect the one-phonon density of states. In the antiferromagnetic phase of the alloys ($x>0.6$) and in the spin-glass phase ($0.17\ensuremath{\le}x\ensuremath{\le}0.6$), a new low-energy Raman line appears. We attribute it to an inelastic scattering involving the emission or absorption of a magnon. The polarization features and the temperature dependence of the magnon line are consistent with this assignment.