Contribution of iron clusters to the magnetic properties of Pb$_{1-y}$Fe$_{y}$Te alloys

The field dependences of the magnetization (temperatures $T$ = 2.0–70 K, magnetic fields $B\le$ 7.5 T) of the samples from a single-crystalline Pb$_{1-y}$Fe$_{y}$Te ingot ($y$ = 0.02) grown by the Bridgman method are studied. It is established that the sample magnetization contains several major contributions such as the paramagnetism of iron ions, diamagnetism of the crystal lattice, and the contributions of charge carriers and clusters of iron atoms. The field dependences of the paramagnetic contribution of iron ions and the contribution of clusters of iron atoms are approximated by theoretical dependences based on the Brillouin and Langevin functions, respectively. The average concentrations and magnetic moment of clusters as well as the total magnetic momentum of clusters in the volume unit in the samples upon increasing the impurity concentration along the ingot are determined.