Effect of a nickel impurity on the galvanomagnetic properties and electronic structure of PbTe

The phase and elemental composition and galvanomagnetic properties (4.2 $\le T\le$ 300 K, B $\le$ 7 T) of Pb$_{1-y}$Ni$_{y}$Te alloys are studied at a variation of the nickel impurity concentration along the single-crystal ingot synthesized by the Bridgman–Stockbarger technique. It is shown that the solubility of nickel does not exceed 0.35 mol.%. Anomalous temperature dependences of the Hall coefficient and temperature and field dependences of magnetoresistance are found. To explain the results, it is assumed that an $n$-type inversion layer appears on the surface of the samples and that there are several competing conduction mechanisms in the samples. A model of the Pb$_{1-y}$Ni$_{y}$Te electronic structure is proposed that assumes pinning of the Fermi level within the Ni impurity band, located at the edge of the valence band and moving deeper into it with increasing temperature.