Superconductivity in iron silicide Lu2Fe3Si5 probed by radiation-induced disordering

Abstract

Resistivity ρ(T), Hall coefficient RH(T), superconducting temperature Tc, and the slope of the upper critical field −dHc2/dT were studied in poly- and single-crystalline samples of the Fe-based superconductor Lu2Fe3Si5 irradiated by fast neutrons. Atomic disordering induced by the neutron irradiation leads to a fast suppression of Tc similarly to the case of doping of Lu2Fe3Si5 with magnetic (Dy) and nonmagnetic (Sc, Y) impurities. The same effect was observed in a novel FeAs-based superconductor La(O-F)FeAs after irradiation. Such behavior is accounted for by strong pair breaking that is traceable to scattering at nonmagnetic impurities or radiation defects in these unconventional superconductors. In such superconductors, the sign of the order parameter changes between the different Fermi sheets (s± model). Some relations that are specified for the properties of the normal and superconducting states in high-temperature superconductors are also observed in Lu2Fe3Si5. The first is the relationship −dHc2/dT ∼ Tc, which allows us to assign the compound Lu2Fe3Si5 to type II superconductors in the clean limit. The second is a correlation between the low-temperature linear coefficient a in the resistivity ρ = ρ0 + a1T, which appears presumably due to the scattering at magnetic fluctuations, and Tc, this correlation being an evidence of a tight relation between the superconductivity and magnetism. Data point to an unconventional (nonphononic) mechanism of superconductivity in Lu2Fe3Si5 and probably in some other Fe-based compounds, which can be fruitfully studied via the radiation-induced disordering.

Source-reported materials — not catalogue approval

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