Conventional isotropic s-wave superconductivity with strong electron-phonon coupling in Sc5Rh6Sn18

Abstract

Sc5Rh6Sn18 is a diamagnetic metallic compound (space group: I41/acd, a≈13.5Å, c≈27.1Å) which becomes superconducting (sc) at Tc=5.15K. The sc state was studied on single-crystal samples by temperature- and field-dependent electrical resistivity, specific heat, and muon-spin rotation (μSR) spectroscopy. No anisotropy of the upper critical field Bc2=7.75T is observed. Analyses of specific heat indicate enhanced values of the jump [Δcp/(γtotTc)=1.58] and of the energy gap ratio [Δ(0)/(kBTc)=2.39] as well as an exponential decrease of the electronic contribution below Tc/2. Together with the saturation of the superfluid density for T<3K observed by μSR spectroscopy these findings lead us to classify Sc5Rh6Sn18 as a moderately strong coupled isotropic s-wave superconductor. However, above Tc, the crystals reveal a surprisingly anisotropic and large resistivity of 2.5–4.5mΩ m with metalliclike behavior perpendicular to the c axis and by a factor of ∼2 larger parallel to c, which decreases upon increasing temperature. These observations are discussed in connection to a characteristic intrinsic disorder in the crystal structure of Sc5Rh6Sn18.

Source-reported materials — not catalogue approval

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