Dualism of the 4f electrons and high-temperature antiferromagnetism of the heavy-fermion compound YbCoC${}_2$

Abstract

We report on the first study of the noncentrosymmetric ternary carbide YbCoC${}_2$. Our magnetization, specific heat, resistivity and neutron diffraction measurements consistently show that the system behaves as a heavy-fermion compound, displaying an amplitude-modulated magnetic structure below the Néel temperature reaching $T_N$ = 33 K under pressure. Such a large value, being the highest among the Yb-based systems, is explained in the light of our ab initio calculations, which show that the 4f electronic states of Yb have a dual nature -- i.e., due to their strong hybridization with the 3d states of Co, 4f states expose both localized and itinerant properties.

25 pages, 8 figures, includes supplement

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• Multiconfigurational nature of 5f orbitals in uranium and plutonium intermetallics
• Fragile antiferromagnetism in the heavy-fermion compound YbBiPt
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