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The galvanomagnetic properties of Pb 1-x-y Ge x Cr y Te in the temperature range 4.2-300 K under variation of the alloy composition (x ≤ 0.13, y ≤ 0.05) and under hydrostatic compression (P≤17 kbar) have been investigated. Pressure dependences of the electron concentration and Fermi energy were obtained. In the frame of the Kane dispersion relation theoretical dependences of electron concentration and Fermi energy were calculated and parameters of chromium impurity band were estimated. Magnetic field dependences of the Hall coefficient under variation of germanium content and under pressure were measured. It is shown, that existence of two conductivity mechanisms should be taken into account: conduction band conductivity and electron-type conductivity via chromium impurity band states. In terms of the two-band conduction model the main parameters of charge carriers were obtained. Experimental results are discussed taking into account the diagram of the electronic structure reconstruction under pressure, assuming finite capacity, electron filling and widening of the impurity band.

The effect of ytterbium impurity on the magnetic and galvanomagnetic properties of new diluted magnetic semiconductors Pb1−xSnxTe:Yb was investigated. Impurity-related Curie–Weiss paramagnetism was revealed. The concentration of magnetic centers and the ytterbium impurity-band occupancy as a function of impurity content were determined. The results are discussed assuming the formation of a ytterbium-induced level under the valence-band top and a variation of the magnetic centers concentration due to changing of the mutual arrangement of the valence band, impurity level and Fermi-level position. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)