EPR Study of the Antiferromagnetic Phase Transition in (Cd, Mn)S

The antiferromagnetic phase transition of octahedrally coordinated (Cd. Mn)S single crystals with Mn concentrations 0.8 ≦ x Mn ≦ 1 is studied by EPR measurements in the temperature range 80 to 550 K. The width of the Mn 2+ EPR line is found to increase with decreasing temperature nearly proportional to ( T ‐ T N )s −1 due to a corresponding decrease of the spin‐spin relaxation time. The Néel temperature T N for the transition from the paramagnetic into the (disordered) antiferromagnetic phase being determined from the linewidth divergence decreases strongly with decreasing x Mn. The results are discussed in connection with actual EPR investigations of (Cd, Mn) and (Zn, Mn) chalcogenide mixed crystals with zincblende/wurtzite structure for lower Mn concentrations. The EPR signal below T N being observed in the case of polycrystalline thin films or powder samples is ascribed to surface near regions of the microcrystals.