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arXiv · 1605.00896

T/B scaling without quasiparticle mass divergence: YbCo2Ge4

A. Sakai·K. Kitagawa·K. Matsubayashi·M. Iwatani·P. Gegenwart
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Abstract

YbCo$_2$Ge$_4$ is a clean paramagnetic Kondo lattice which displays non-Fermi liquid behavior. We report a detailed investigation of the specific heat, magnetic Grüneisen parameter ($Γ_{\rm mag}$) and temperature derivative of the magnetization ($M$) on a high-quality single crystal at temperatures down to $0.1$~K and magnetic fields up to 7~T. $Γ_{\rm mag}$ and $dM/dT$ display a divergence upon cooling and obey $T/B$ scaling. Similar behavior has previously been found in several other Yb-based Kondo lattices and related to a zero-field quantum critical point without fine tuning of pressure or composition. However, in the approach of $B\rightarrow 0$ the electronic heat capacity coefficient of YbCo$_2$Ge$_4$ saturates at low $T$, excluding ferromagnetic quantum criticality. This indicates that $T/B$ scaling is insufficient to prove a zero-field quantum critical point.

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A. Sakai, K. Kitagawa, K. Matsubayashi, M. Iwatani, P. Gegenwart. 2016-06-28. T/B scaling without quasiparticle mass divergence: YbCo2Ge4. https://doi.org/10.1103/physrevb.94.041106

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