Superconductivity of the Filled Skutterudite ThPt₄Ge₁₂Investigated by Muon Spin Rotation

Abstract

The superconducting state of the filled skutterudite ThPt 4 Ge 12 has been investigated by the zero-field longitudinal and transverse-field muon spin rotation technique. The deduced temperature dependence of the muon spin depolarization rate, σ s , at 0.04 T has been analyzed in terms of a phenomenological powerlaw behavior and a model appropriate for clean limit superconductors. The estimated effective Fermi temperature T F = 87 K has been compared by means of the Uemura plot with those derived for other superconducting systems. The gap parameter ∆(0)/k B = 7.7(1) and the magnetic penetration depth λ = 156(5) nm, obtained from the muon data, confirm the specific heat results reported before.

Heavy-fermion superconductivity in

“…These features suggest the presence of antiferromagnetic spin fluctuations and hint at an unconventional character of the superconducting state that possibly emerges in the proximity of a quantum critical point instability, alike in the related HF superconductors CeT In 5 and Ce 2 T In 8 with T = Co, Rh and Ir [4]. The latter hypothesis seems supported by recently obtained muon spin rotation spectroscopy and inelastic neutron scattering data [5], which clearly evidence magnetically-driven superconducting behavior in Ce 2 PdIn 8 , even if long-range AF order is actually absent as an intrinsic property of this compound.…”

Kaczorowskiet al.Reply:

“…These features suggest the presence of antiferromagnetic spin fluctuations and hint at an unconventional character of the superconducting state that possibly emerges in the proximity of a quantum critical point instability, alike in the related HF superconductors CeT In 5 and Ce 2 T In 8 with T = Co, Rh and Ir [4]. The latter hypothesis seems supported by recently obtained muon spin rotation spectroscopy and inelastic neutron scattering data [5], which clearly evidence magnetically-driven superconducting behavior in Ce 2 PdIn 8 , even if long-range AF order is actually absent as an intrinsic property of this compound. …”

Quasi-two-dimensional Fermi surfaces of the heavy-fermion superconductorCe2PdIn8

“…Non-Fermi-liquid behavior was observed in both macroscopic [6-10] and microscopic [11,12] measurements at low temperature, implying that Ce 2 PdIn 8 is located very close to a QCP. It was further suggested that a twodimensional (2D) SDW-type QCP is induced by magnetic field near the upper critical field, H c2 ≈ 2 T [9].…”