Resistivity Minimum in Antiferromagnetic Cr–Co Alloys

Abstract

The electrical resistivity of Cr–Co alloys containing up to 8 at.% Co is measured in detail over the temperature range 1.8 K–340 K. The resistivity minimum is observed in the alloys containing more than 2 at.% Co. The temperature of the minimum and the depth of the minimum increase rapidly with the concentration of Co, depending on c and c³, respectively (c is the concentration of Co). The measured resistivity of the alloy containing 4 at.% Co shows a constant value below about 4 K, decreases with increasing temperature in proportion to T² up to about 14 K and exhibits a minimum. These results suggest that the resistivity minimum in Cr–Co alloys is due to the Kondo effect by pairs of Co atoms, not by isolated Co atoms. The Kondo temperature T_K of Cr-4 at.% Co alloy is estimated to be about 280 K and is considerably high.