  Superconducting properties of the polycrystalline Zr2Ru3Si4 were investigated
by the electrical resistivity, magnetization and specific heat. By these
measurements, bulk superconductivity with transition temperature Tc = 5.5 K was
confirmed. Moreover, Zr2Ru3Si4 was found to be a type-II and
intermediate-coupling superconductor. Interestingly, the electronic specific
heat shows a deviation from a one-gap s-wave model and Hc2(T) shows unusual
positive curvature in the vicinity of Tc. The first principle's calculation
shows the existence of plural anisotropic Fermi surfaces. These results suggest
that Zr2Ru3Si4 is not an isotropic single-gap superconductor, but possibly a
multi-gap or an anisotropic gap superconductor.
