Magnetic contribution to the specific heat of IV-VI semimagnetic semiconductors

Temperature dependence of magnetic specific heat has been studied experimentally and theoretically in semimagnetic semiconductors Pb_1-xMn_xTe, Pb_1-xEu_xTe, and Pb_1-xGd_xTe with x of about 0.03 over the temperature range from 0.5 to 15 K, in magnetic fields up to 4 T. There was usually a pronounced maximum in the magnetic specific heat below 2 K at zero magnetic field. The maximum shifted toward higher temperatures with increasing magnetic field. The data for the three materials could not be described in the framework of one theoretical model. For each material a different model was applied.