Yb3Rh4Sn13: Two-gap superconductor with a complex Fermi surface

Abstract

Structural and physical properties of the Yb3Rh4Sn13 Remeika phase are investigated on large single crystals grown from Sn-flux. It crystallizes with disordered Y3Co4Ge13 structure type [space group Pm3¯n, a=9.6709(2) Å], where the 24k crystallographic site occupied by Sn atoms is split. Yb3Rh4Sn13 is a superconductor (SC) with the critical temperature Tc=7.63(5) K, lower [Bc1=14.5(5) mT] and upper [Bc2(0)=2.89(5) T] critical fields, as well as a clear peak effect with B*(0)=1.96(9) T observed in the M(H) loops. Bc2(Tc) can be described by the sum of two Werthamer-Helfand-Hohenberg equations. A γ(B)∝B0.75 dependency is found. The electronic specific heat below Tc follows an exponential function including 87% of a strongly coupled [Δ1/kBTc=3.52(1)] and 13% of a conventional s-wave-like [Δ2/kBTc=1.32(1)] gap. The observations are in line with Yb3Rh4Sn13 being a two-gap SC. The Remeika phase reveals a complex electronic band structure studied by Hall coefficient (RH) measurements and calculations performed within the density functional theory. A “rattling” effect in Yb3Rh4Sn13 is discussed based on structural refinements and phononic contributions to its specific heat capacity.

Source-reported materials — not catalogue approval

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