A phenomenological description of the paramagnet-antiferromagnet transition in Cd_1-xMn_xTe

Magnetic susceptibility, specific heat and neutron diffraction studies of Cd_1-xMn_xTe indicate that for 0.60≤x≤0.71 the system orders antiferromagnetically at low temperatures. However, there is a large discrepancy between the transition temperatures suggested by various experiments. We present a simple cluster model of the transition process with a distribution of Néel temperatures. The distribution function f(T_N) may be obtained from the temperature dependence of the magnetic specific heat. The temperature variations of the intensity of neutron magnetic reflections and the magnetic susceptibility, calculated on the basis of f(T_N), show a good agreement with the experimental results.