Magnetic, Thermodynamic, and Transport Properties of Layered Arsenides BaRu$_{2}$As$_{2}$ and SrRu$_{2}$As$_{2}$

As part of our effort to search for novel superconductors related to the FeAs high-$T$ superconductors, we have synthesized polycrystalline samples of BaRu$_{2}$As$_{2}$ and SrRu$_{2}$As$_{2}$. The magnetic, transport and thermodynamic properties of the samples were investigated by means of magnetic susceptibility $\chi(T)$, electrical resistivity $\rho(T)$, and heat capacity $C_{p}(T)$ measurements. The temperature dependence of $\rho$ indicates metallic character for both compounds with a residual resistivity ratio $\rho$(310 K)/$\rho$(2 K) of 17 and 7 for the Ba and Sr compounds, respectively. The $C_{p}(T)$ results indicate a low density of states at the Fermi level with the low-$T$ Sommerfeld coefficient $\gamma \simeq 4.9$ and $4.13$ mJ/mole K$^{2}$ for the Ba and Sr compounds, respectively. The Debye temperature $\Theta_{D}$ was estimated to be $270$ K and $260$ K for the Ba and Sr compounds, respectively. The $\chi (T)$ was found to be diamagnetic with a small absolute value for both the compounds. No evidence for superconductivity, a spin density wave, or a structural transition was observed from the $C_{p}(T)$ and $\rho(T)$ measurements down to $2$ K. However, the $\chi(T)$ data for SrRu$_{2}$As$_{2}$ exhibit a cusp at $\sim 190$ K, possibly an indication of a structural and/or magnetic transition.\\ \noindent * Supported by the USDOE under contact No. DE-AC02-07CH11358.