Temperature coefficient of movement of the resonance level of iron in Pb$_{1-x-y}$Sn$_{x}$Fe$_{y}$Te alloys

The phase composition, the elemental composition and temperature dependences of the resistivity and of the Hall coefficient (temperature interval 4.2 $\le T\le$ 300K, magnetic fields B $\le$ 0.07 T) in Pb$_{1-x-y}$Sn$_{x}$Fe$_{y}$Te alloys are studied at variation of the tin and iron concentrations along the single-crystal ingots synthesized by the Bridgman–Stockbarger technique. The distributions of tin and iron along the ingots are obtained and anomalous temperature dependences of the Hall coefficient, associated with the pinning of the Fermi level by the resonant level of iron, located in the valence band, are found. The analysis of the experimental results is carried out in the framework of the model of the electronic structure rearrangement, involving the movement of the iron level relative to the top of the valence band with increasing tin concentration and temperature. The temperature coefficient of the movement of the level of iron with respect to the middle of the gap is determined and the possible diagrams for the rearrangement of the electronic structure with increasing temperature in the alloys with normal spectrum (0.06 $\le x\le$ 0.35) are proposed.