MAGNETIC-PROPERTIES OF SN1-XGDXTE ESS-THAN-OR-EQUAL-TO-X-LESS-THAN-OR-EQUAL-TO-0.09)

Magnetic, transport and structural properties of bulk crystals of Sn1- xGdxTe with Gd content 0.002 < x < 0.09 and varying carrier concentrat ions obtained by an isothermal annealing were studied in the temperatu re range T = 1.5-80 K. We found the effect of resonant increase in ant iferromagnetic spin-spin exchange interactions in the crystals with 0. 025 less than or equal to x less than or equal to 0.05. No effect was found in crystals either with higher (x > 0.05) or with lower (x < 0.0 25) Gd concentration. The observed Gd composition dependence of the ma gnetic and transport properties of SnGdTe can be explained in a propos ed model relating these experimental properties to the Gd composition induced shift of the position of Gd-3+/2+ level with respect to the to p of the valence band of SnGdTe.