FAR-INFRARED SPIN-RESONANCE IN THE II-VI DILUTED MAGNETIC SEMICONDUCTORS ZN1-XMNXSE, CD1-XMNXSE, AND ZN1-XCOXS

Exchange interactions in the diluted magnetic semiconductors Zn1-xCoxS , Zn1-xMnxSe, and Cd1-xMnxSe were studied by electronic paramagnetic r esonance in the far-infrared region in a high magnetic field up to 40 T. For x approximate to 5%, transmission spectra exhibit very sharp sa tellite lines on both sides of the single magnetic-ion resonance. Thes e features are attributed to the exchange of coupled spin pairs. A cal culation of the energy levels of the pairs, including Dzyaloshinskii-M oriya (DM) effects and symmetrical exchange terms of the interaction t enser, allows us to extract from the measurements the values of the an isotropic exchange constants: D-e=0.014 K and D-DM=0.18 K in Zn1-xMnxS e, D-e=0.009 K and D-DM=0.12 K in Cd1-xMnxSe, and D-e=0.06 K in Zn1-xC oxS. The values of the DM constants compare well with predictions by L arson and Ehrenreich. Moreover, in the case of cobalt, the occurrence of an absorption peak at half-field is interpreted by taking the symme tric anisotropic terms into account.