Thermal Conductivity of Cr-Rich Cr-Si Between 3 and 300 K

The Cr-Si system exhibits above about 1 at% Si a large first order antiferromagnetic transition which is not well understood so far. Simultaneous measurements of thermal conductivity λ and electrical resistivity ρ on two Cr-Si alloys of 0.9 and 1.4 at% Si in the temperature range 3-300 K have been carried out to gain further insight into the role of electronic and lattice properties at the magnetic transition at the Neel point TN. At TN a step-like change in λ was observed for the Cr-1.4 at% Si alloy while λ was almost featureless for the lower concentration. The Lorenz number L, which was found to lie in the range 4-7 WΩ deg-2, exhibits a broad peak centered around 60 K. Analysis of the λ-data reveals below 50 K a dominating lattice thermal conductivity term with a T2 dependence and decreasing in magnitude with increasing Si concentration. Around TN electronic contributions are found to dominate the thermal conductivity although both lattice and electronic effects seem to be responsible for the enhancement of L over the Sommerfeld value L0.