Dependence of EPR in diluted magnetic semiconductors on the host lattice

We have studied the EPR in six wide-gap diluted magnetic semiconductors: ${\mathrm{Cd}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{Mn}}_{\mathrm{x}}$Te, ${\mathrm{Cd}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{Mn}}_{\mathrm{x}}$Se, ${\mathrm{Cd}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{Mn}}_{\mathrm{x}}$S, ${\mathrm{Zn}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{Mn}}_{\mathrm{x}}$Te, ${\mathrm{Zn}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{Mn}}_{\mathrm{x}}$Se, and ${\mathrm{Zn}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{Mn}}_{\mathrm{x}}$S, all containing about 10 at. % Mn, in order to determine the extent to which the EPR of the magnetic ions depends on their environment in these materials. The EPR linewidth and intensity as a function of temperature was obtained by measuring Faraday rotation and ellipticity associated with the resonance, a technique suitable for EPR studies when the resonance is very broad. It was found that, although the behavior of the ${\mathrm{Mn}}^{2+}$ EPR is qualitatively the same in all the above materials, its intensity and linewidth show a striking and systematic dependence on the nonmagnetic host lattice. Specifically, for a given group-VI element (anion) the resonance becomes broader and weaker as the atomic number of the group-II element (nonmagnetic cation) decreases; but, in contrast, for a given cation the resonance becomes broader and weaker as the atomic number of the anion increases. This provides interesting insights into the nature of the interaction between ${\mathrm{Mn}}^{2+}$ ions in diluted magnetic semiconductors.