Exotic Heavy-Fermion State in Filled Skutterudite SmOs4Sb12

TL;DR

This study reveals an unconventional heavy-fermion state in SmOs4Sb12, characterized by enhanced specific heat and resistivity coefficients, with magnetic ordering likely arising from itinerant quasiparticles, differing from typical Ce-based heavy fermion systems.

Contribution

The paper reports the discovery of an unconventional heavy-fermion state in SmOs4Sb12 with unique thermodynamic and transport properties, indicating a different origin of heavy quasiparticles.

Findings

Enhanced electronic specific heat coefficient (gamma=0.82 J/K^2mol)

Large resistivity quadratic coefficient (A)

Weak ferromagnetic ordering below 3 K

Abstract

Specific heat and transport measurements have revealed an unconventional heavy-fermion (HF) state in SmOs4Sb12 single crystals. The electronic specific-heat coefficient (gamma=0.82 J/K^2mol) and the coefficient (A) of the quadratic temperature dependence of electrical resistivity are largely enhanced, although the ratio A/gamma^2 is reduced from the Kadowaki-Woods ratio of HF materials. Both gamma and A do not show any significant decrease in applied field in contrast with Ce-based HF compounds, suggesting an unconventional origin of the heavy quasiparticles. A weak ferromagnetic ordering sets in below about 3 K, probably originating in the itinerant quasiparticles.