  We report the results of electrical resistivity, magnetic and thermodynamic
measurements on polycrystalline SnSb, whose structure consists of stacks of Sb
bilayers and Sn4Sb3 septuple layers along the c-axis. The material is found to
be a weakly coupled, fully gapped, type-II superconductor with a bulk Tc of
1.50 K, while showing a zero resistivity transition at a significantly higher
temperature of 2.48 K. The Sommerfeld coefficient and upper critical field,
obtained from specific heat measurements, are 2.29 mJ/mol K and 520 Oe,
respectively. Compositional inhomogeneity and strain effect at the grain
boundaries are proposed as possible origins for the difference in resistive and
bulk superconducting transitions.In addition, a comparison with the rock-salt
structure SnAs superconductor is presented. Our results provide the first clear
evidence of bulk superconductivity in a natural superlattice derived from a
topological semimetal.

Superconductivity