RAMAN-SCATTERING FROM OPTICAL PHONONS AND MAGNETIC EXCITATIONS IN CD1-XMNXSE AND CD1-XMNXS

The Raman spectra of Cd1-xMnxSe and Cd1-xMnxS are investigated for various Mn2+ concentrations x. Both Cd1-xMn(x)Se and Cd1-xMn(x)S have the wurtzite structure and have point-group symmetry C6-upsilon. Cd1-xMnxSe shows a two-mode behavior, whereas Cd1-xMnxS, in which the modes associated with Mn2+ appear in between the LO and TO phonons, shows an intermediate behavior. The frequencies of the TO modes and nonpolar E2 modes are found not to depend significantly on the composition. We believe that this is due to the absence of polarization fields associated with this mode. The modified random-element-isodisplacement model gives a good description of optical phonons in Cd1-xMnxSe. In an external magnetic field, a Raman line associated with a spin-flip excitation of Mn2+ and its combination with LO phonons are observed.