Effect of a Nickel Impurity on the Galvanomagnetic Properties and Electronic Structure of PbTe

The phase and elemental composition and galvanomagnetic properties of the Pb 1 – y Ni y Te alloys at temperatures of 4.2 K < T < 300 K in magnetic fields of B < 7 T are investigated upon a variation in the nickel-impurity concentration along a single-crystal ingot synthesized by the Bridgman–Stockbarger technique. The solubility of nickel is shown to be no more than 0.35 mol %. The anomalous temperature dependences of the Hall coefficient and temperature and field dependences of the magnetoresistance are established. The results obtained are explained under the assumption of the formation of an inversion layer with n -type conductivity on the sample surface and the existence of several competing conductivity mechanisms in the samples. A model of the Pb 1 – y Ni y Te electronic structure is proposed that suggests Fermi-level pinning within the Ni impurity band located at the edge of the valence band and moving deeper into it with increasing temperature.