Enhanced Quasiparticle Heat Conduction in the Multigap SuperconductorLu2Fe3Si5

Abstract

Thermal transport measurements have been made on the Fe-based superconductor Lu2Fe3Si5 (T(c) ∼ 6 K) down to a very low temperature T(c)/120. The field and temperature dependences of the thermal conductivity confirm the multigap superconductivity with fully opened gaps on the whole Fermi surfaces. In comparison to MgB2, Lu2Fe3Si5 reveals a remarkably enhanced quasiparticle heat conduction in the mixed state. The results can be interpreted as a consequence of the unequal weight of the Fe 3d-electron character among the distinct bands.

Electronic structure and Fermi surface of iron-based superconductors R2Fe3Si5 (R = Lu;Y;Sc) from first principles

“…Nevertheless, any unconventional (non-phononic) mechanism of their superconductivity may be similar to those already postulated for a majority of iron-based compounds. These conclusions are in accord with the findings of recent various experiments presented in [28][29][30][31][32]. …”

“…In analogy to MgB2 [33], the postulated source of the multi-gap SC in Lu2Fe3Si5 is first of all weak inter-band interactions between the multiple bands having different dimensionality [28]. In addition, the iron silicides exhibit moderately strong correlations between the Fe 3d electrons [29]. For the (Lu;Y;Sc)2Fe3Si5 series, Fig.…”

“…The anisotropy of their superconducting properties, anomalous upper critical fields (in Lu2Fe3Si5), and inter-band electron scattering in the case of two weak-coupled distinct gaps opened on the whole Fermi surface (FS) sheets, indicated that they are rather quasi-2D superconductors [26][27][28][29]. Furthermore, some recent works [30][31][32] focused on the effect of doping by non-magnetic impurities and atomic disorder induced by the neutron irradiation, both causing a fast suppression of TC in Lu2Fe3Si5, have questioned the conventional (phononic) mechanism of SC in the (Lu;Y;Sc)2Fe3Si5 family, revealing the significance of spin fluctuations in formation of the SC state [32].…”

Possible multigap superconductivity and magnetism in single crystals of superconducting La2Pt3Ge5and PrSung1, Roh2, Kim3 et al. 2012Phys. Rev. B257230View full textAdd to dashboardCite

“…[17] More recently, fully opened superconducting gaps were confirmed by measuring specific heat, [18] penetration depth, [19] and thermal conductivity. [20] Furthermore, different anisotropies of the two bands in Lu 2 Fe 3 Si 5 was also recently reported. [21] Because of their various interesting properties, the search for new 235 compounds that might possess higher T c with magnetic ordering is of great importance to the study of superconductivity, magnetism and the relationship between them.…”

The electronic structure of rare-earth iron silicide R2Fe3Si5 superconductors

“…The interband electron scattering between these two weak-coupled gaps opened on the whole Fermi surface (FS) is the reason for an observed anisotropy of superconducting properties in the 235-type iron silicides being rather quasi-2D superconductors [24,25,26,27,28,29]. Furthermore, the conventional (phononic) character of an SC mechanism in Lu 2 Fe 3 Si 5 has been questioned by a fast suppression of T c caused by non-magnetic impurities and atomic disorder induced by the neutron irradiation [30,31,32].…”