TRANSPORT AND MAGNETIC STUDY OF GD IONS IN PB1-YSNYTE

Electric conductivity, Hall effect and magnetic susceptibility of Pb1- x-ySnyGdxTe mixed crystals with 0.13 less than or equal to y less than or equal to 0.93 and 0.001 less than or equal to x less than or equal to 0.04 were experimentally studied over the temperature range 4K les s than or equal to T less than or equal to 300 K. The incorporation of Gd ions into the Pb1-ySnyTe matrix results in semi-metallic n-type co nductivity of the crystals with y < 0.6. For crystals with y > 0.6 one observes only semi-metallic p-type conductivity. We present a model e xplaining these results in terms of the Sn composition dependence of t he location of Gd2+/3+ level with respect to the band edges of PbSnGdT e.