Two energy gaps in superconducting Lu2Fe3Si5 single crystal derived from the temperature dependence of lower critical field Hc1(T)

We report a detailed study of in-plane lower critical field H c1(T) and penetration depth λ ab(T) of the Lu 2Fe 3Si 5 superconductor. Two pronounced changes of the H c1 curvature are observed on the H c1(T) curve around 0.4T c and 0.65T c, respectively, which are attributed to the two-band nature of superconductivity in Lu 2Fe 3Si 5. The penetration depth of λ ab(T) follows a power law (∼T n) below 0.4T c, with n = 2.5 close to the values reported for the FeAs-pnictides, suggesting possible s ±-wave pairing in Lu 2Fe 3Si 5. Temperature dependence of H c1 can be well fitted by the two-gap BCS model in the full temperature region using two superconducting gaps Δ 1 = 0.19 ± 0.1 meV and Δ 2 = 1.02 ± 0.1 meV. © 2012 Elsevier B.V. All rights reserved.status: publishe