Paramagnetic--Spin-Glass--Antiferromagnetic Phase Transitions in Cd1--xMnxTe From Specific Heat and Magnetic Susceptibility Measurements

Low-temp. specific heat and low-field magnetic susceptibility were measured in Cd1--xMnxTe mixed crystals for 0.002 < = x < = 0.70. Three regions of composition can be distinguished in both experiments. For x # < 0.17 the crystal is paramagnetic at all temp. For 0.17 # < x # < 0.7, a spin-glass phase is observed, as evidenced by the characteristic cusp in the susceptibility and a linear temp. dependence of the specific heat in the low-temp. regions. Because the material is an insulator at low temp. and the Mn interactions are only antiferromagnetic, it is believed that the observed spin-glass phase is produced by the frustration of the lattice. For x = 0.7 an antiferromagnetic phase is observed. To understand the experimental behavior of the specific heat and susceptibility as a function of temp. and magnetic field for 0.002 # < x # < 0.17, it is assumed that the distribution of Mn ions deviates strongly from a random distribution. The number of pairs is more than doubled for x = 0.05, and 30% higher for x = 0.1, than statistically predicted. The number of larger clusters, like triplets, is also significantly higher.40 refs.--AA