Magnetic field induced Raman excitations in Zn$_{1-x}$Cr$_{x}$Te, Cd$_{1-x}$Cr$_{x}$Te and Cd$_{1-x}$Cr$_{x}$Se

Raman electron paramagnetic resonance(Raman-EPR) of the transitions due to the $\Delta $m$_{s}=\pm $1 spin-flip of the 3d electrons of Cr$^{+}$ in Zn$_{1-x}$Cr$_{x}$Te and Cd$_{1-x}$Cr$_{x}$Te are observed at $\omega _{PM}$=g(Cr$^{+})\mu _{B}$B, g(Cr$^{+})$=2.0041$\pm $ 0.0095 and 2.0039 $\pm $ 0.0093, respectively. Raman lines appear at $\omega _{LO}\pm $ n$\omega _{PM}$, n=1,2 and 3, resulting from the strong Fr\"{O}hlich interaction with LO phonon. The intensity of $\omega _{PM}$ can be enhanced through the photo-generation process Cr$^{2+}\to $ Cr$^{+}$; photoluminescence spectra reveal signatures of excitons bound to Cr$^{+}$ acceptors in Zn$_{1-x}$Cr$_{x}$Te. The resonance profile of $\omega _{PM }$shows that the strong resonant enhancement is mediated via an exciton bound to a neutral acceptor. Spin flip Raman scattering (SFRS) at $\omega _{SFR}$ from donor-bound electrons in Cd$_{1-x}$Cr$_{x}$Se, as well as in pure CdSe, are observed, in turn yielding the s-d exchange energy. The magnetization of Cd$_{1-x}$Cr$_{x}$Se is intermediate between van Vleck and a B$_{2}$ Brillouin paramagnetism. The linear dependence of the s-d exchange energy as a function of magnetization yields the s-d exchange constant in Cd$_{1-x}$Cr$_{x}$Se, $\alpha $N$_{0}$=(213.7 $\pm $13) meV.