Magnetic Properties of Yb$_{2}$Pt$_{2}$Pb with the Shastry-Sutherland Lattice

We have synthesized single crystals of Yb$_{2}$Pt$_{2}$Pb, which crystallize in the tetragonal U$_{2}$Pt$_{2}$Sn-type structure. Comparison of the crystal structure with that of other compounds reveals a structure dependent Yb valence state of Yb$_{2}$T$_{2}$M (T=transition metal; M=Cd, In, Sn, and Pb). The magnetic susceptibility $\chi$ of Yb$_{2}$Pt$_{2}$Pb is highly anisotropic. The $\chi_{\lbrack100\rbrack}$ for $B$$\parallel$$\lbrack100\rbrack$ is thirty times larger than $\chi_{\lbrack001\rbrack}$ for $B$$\parallel$$\lbrack001\rbrack$ at the lowest temperatures. A broad maximum in $\chi_{\lbrack100 \rbrack}$ is found around 3 K just above magnetic transition temperature 2.07 K. In agreement, the electrical resistivity shows a broad maximum around 5 K and the specific heat shows a long tail up to 8 K, due to the magnetic frustration originating from antiferromagnetic exchange interaction between Yb ions arranged in the network of the Shastry-Sutherland lattice.