Magnetic, thermal, and transport properties of layered arsenides BaRu2As2 and SrRu2As2

The magnetic, thermal, and transport properties of polycrystalline BaRu2As2 and SrRu2As2 samples with the ThCr2Si2 structure were investigated by means of magnetic susceptibility chi(T), electrical resistivity rho(T), and heat capacity C-p(T) measurements. The temperature (T) dependence of rho indicates metallic character for both compounds with residual resistivity ratios rho(310 K)/rho(2 K) of 17 and 5 for the Ba and Sr compounds, respectively. The C-p(T) results reveal a low-T Sommerfeld coefficient gamma=4.9(1) and 4.1(1) mJ/mol K-2 and Debye temperature Theta(D)=271(7) and 271(4) K for the Ba and Sr compounds, respectively. The chi(T) was found to be diamagnetic with a small absolute value for both compounds. No transitions were found for BaRu2As2 above 1.8 K. The chi(T) data for SrRu2As2 exhibit a cusp at similar to 200 K, possibly an indication of a structural and/or magnetic transition. We discuss the properties of BaRu2As2 and SrRu2As2 in the context of other ThCr2Si2-type and ZrCuSiAs-type transition metal pnictides.