Unusually strong electronic correlation and field-induced ordered phase in YbCo$_2$

J. Valenta; N. Tsujii; H. Yamaoka; F. Honda; Y. Hirose; H. Sakurai; N. Terada; T. Naka; T. Nakane; T. Koizumi; H. Ishii; N. Hiraoka; T. Mori

doi:10.1088/1361-648x/acca5a

arXiv · 2204.12025

Unusually strong electronic correlation and field-induced ordered phase in YbCo$_2$

J. Valenta·N. Tsujii·H. Yamaoka·F. Honda·Y. Hirose·H. Sakurai·N. Terada·T. Naka·T. Nakane·T. Koizumi·H. Ishii·N. Hiraoka·T. Mori

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Abstract

We report the first study of electrical resistivity, magnetization, and specific heat on YbCo$_2$. The measurements on a single-phased sample of YbCo$_2$ bring no evidence of magnetic ordering down to 0.3 K in a zero magnetic field. The manifestations of low Kondo temperature are observed. The specific heat value divided by temperature, C/T, keeps increasing logarithmically beyond 7 J/mol.K2 with decreasing temperature down to 0.3 K without no sign of magnetic ordering, suggesting a very large electronic specific heat. Analysis of the magnetic specific heat indicates that the large portion of the low-temperature specific heat is not explained simply by the low Kondo temperature but is due to the strong intersite magnetic correlation in both the 3d and 4f electrons. Temperature-dependent measurements under static magnetic fields up to 7 T are carried out, which show the evolution of field-induced transition above 2 T. The transition temperature increases with increasing field, pointing to a ferromagnetic character. The extrapolation of the transition temperature to zero field suggests that YbCo$_2$ is in the very proximity of the quantum critical point. These results indicate that in the unique case of YbCo$_2$, the itinerant electron magnetism of Co 3d-electrons and the Kondo effect within the vicinity of quantum criticality of Yb 4f-local moments can both play a role.

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J. Valenta, N. Tsujii, H. Yamaoka, F. Honda, Y. Hirose, H. Sakurai, N. Terada, T. Naka, T. Nakane, T. Koizumi, H. Ishii, N. Hiraoka, T. Mori. 2022-04-26. Unusually strong electronic correlation and field-induced ordered phase in YbCo$_2$. https://doi.org/10.1088/1361-648x%2Facca5a

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