Magnetic Specific Heat of Pb$\text{}_{1-x}$Eu$\text{}_{x}$Te

The temperature dependence of the magnetic specific heat was studied experimentally and theoretically in the semimagnetic semiconductor Pb$\text{}_{1-x}$Eu$\text{}_{x}$Te for x=0.027 and x=0.073, over the temperature range from 0.5 K to 15 K, in magnetic fields up to 2 T. In zero magnetic field at about 2 K there was a broad maximum in the magnetic specific heat, which was much higher than that predicted by the model of superexchange interaction between nearest neighbors; the maximum values increased with magnetic field. The experimental data were analyzed in the framework of a model which takes into account the spin splitting of the ground state of a single Eu2+ ion in the presence of local lattice distortions in the Pb$\text{}_{1-x}$Eu$\text{}_{x}$Te mixed crystal. The model describes well the experimental data, especially for lower x-values, where the contribution from singlets dominates.