Specific-heat evidence for two-gap superconductivity in the ternary-iron silicide Lu2Fe3Si5

We report low-temperature specific-heat studies on the single-crystalline ternary-iron silicide superconductor Lu2Fe3Si5 with T-c=6.1 K down to similar to T-c/20. We confirm a reduced normalized jump in specific heat at T-c, and find that the specific heat divided by temperature C/T shows a sudden drop at similar to T-c/5 and goes to zero with further decreasing temperature. These results indicate the presence of two distinct superconducting gaps in Lu2Fe3Si5, similar to the typical two-gap superconductor MgB2. We also report Hall coefficients, band structure calculations, and the anisotropy of upper critical fields for Lu2Fe3Si5, which support the anisotropic multiband nature and reinforce the existence of two superconducting gaps in Lu2Fe3Si5.