Physical properties of Sm x B 6 single crystals

We study the magnetic susceptibility, electrical resistivity, Hall effect, and heat capacity of single crystals of ${\mathrm{Sm}}_{x}{\mathrm{B}}_{6}$ for $x=1,0.94,0.8,$ and 0.75. Remarkably, the overall properties of the crystals do not qualitatively depend on the density of vacancies. The topological surface states are seen at low temperatures in the electrical transport properties as the bulk conductivity freezes out. Even a large number of Sm vacancies does not close the hybridization gap. The linear term in the specific heat $\ensuremath{\gamma}$, of unclear origin, remains large but decreases gradually with $x$. The shoulder in the density of states, brought by the hybridized $4f$ states and observed in the susceptibility and the specific heat, does not move but decreases its height with decreasing $x$. The specific heat also displays a weak Schottky anomaly at about 1.5 K for all $x$, except for the $x$ = 0.75 sample. This Schottky anomaly is only slightly field dependent and of unknown origin.