Dependence of EPR in diluted magnetic semiconductors on the host lattice

We have studied the EPR in six wide-gap diluted magnetic semiconductors: Cd_1-x{Mn}ₓ$Te, ${Cd}_{1{{-}}x}MnₓSe, Cd_1-x{Mn}ₓ$S, ${Zn}_{1{{-}}x}MnₓTe, Zn_1-x{Mn}ₓ$Se, and ${Zn}_{1{{-}}x}MnₓS, 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 Mn²⁺ 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 Mn²⁺ ions in diluted magnetic semiconductors.