Magnetic properties of diluted magnetic semiconductors Pb1–yFeyTe

Abstract

The phase and elemental composition and magnetic properties (B ≤ 7.5 T, 2.0 K ≤ T ≤ 70 K) of Pb1–yFeyTe alloys were studied under varied impurity concentration along the Bridgman-grown single-crystal ingot. The distribution of iron impurity along the length of the ingot in the main phase and the composition of microscopic inclusions of the second phase were determined. It was established that the magnetization of the samples contains several contributions: the paramagnetic contribution of impurity ions, crystal lattice diamagnetism, as well as the contributions of free charge carriers, charge carriers in the impurity band, clusters of iron ions, and the oscillating contribution of the de Haas–van Alphen effect. These contributions were systematically separated. Using an approximation for the magnetic field and temperature dependences of the impurity-ion contribution by a sum of two terms based on the modified Brillouin functions, we determined the variation of the concentration of iron ions in two different charge states along the ingot. It was shown that the charge carrier concentrations obtained from the de Haas–van Alphen oscillations are in satisfactory agreement with the Hall concentrations, indicating a weak effect of the inclusions of the second phase and magnetic clusters on homogeneity and physical properties of the main phase in Pb1–yFeyTe alloys.