Donor impurity effect on the electric properties of CdCr2S4 single crystals

The effect of indium and gallium admixtures (up to 11 at.%) on the specific electric and magnetic resistance of CdCr2S4 single crystals has been investigated at temperatures up to 300 K. Sharp sensitivity of the conductivity to admixture concentrations is noted. For example, 7-fold increase of gallium concentration reduces the electric resistance 1000 times at 300 K. Application of an external magnetic field sharply reduces the resistance near the Curie point. It has been found that doping of CdCr2S4 single crystals with donor admixtures of indium and gallium brings about abnormal electric properties which are due to the s-d exchange interaction of conduction electrons with magnetic subsystem