Two-gap superconductivity in single crystal Lu2Fe3Si5 from penetration depth measurements
Abstract
Single crystal of Lu2Fe3Si5 was studied with the tunnel-diode resonator technique in Meissner and mixed states. Temperature dependence of the superfluid density provides strong evidence for the two-gap superconductivity with almost equal contributions from each gap of magnitudes 1/kBTc=1.86 and 1/kBTc=0.54. In the vortex state, pinning strength shows unusually strong temperature dependence and is non-monotonic with the magnetic field (peak effect). The irreversibility line is sharply defined and is quite distant from the Hc2(T), which hints on to enhanced vortex fluctuations in this two-gap system. Altogether our findings provide strong electromagnetic - measurements support to the two-gap superconductivity in Lu2Fe3Si5 previously suggested from specific heat measurements.