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キーワード:
Critical temperature, Electric conductivity, Emission spectroscopy, Magnetic anisotropy, Specific heat of liquids, Specific heat of solids, Thermography (temperature measurement), Ytterbium compounds, Critical systems, Ferromagnetics, Kondo lattice systems, Kondo temperatures, Measurements of, Property, Quantum critical, Quantum-critical point, Resonant x-ray emission spectroscopies, Single crystal growth, Fermi liquids
要旨:
We report on single-crystal growth and physical properties of the quantum critical Kondo-lattice system YbNi4(P1-xAsx)2 with 0≤x≤1 which hosts a ferromagnetic quantum critical point at x≈0.1. We performed measurements of the magnetization, electrical resistivity, thermopower, heat capacity, and resonant x-ray emission spectroscopy. Arsenic substitution leads to a homogeneous increase of the unit-cell volume, with well-defined As concentrations in large parts of the single crystals. All data consistently show that with increasing x the Kondo temperature increases, while the magnetic anisotropy observed at low x fully vanishes toward x=1. Consequently, at low temperatures, the system shows a crossover from pronounced non-Fermi liquid behavior for x≤0.2 to a Fermi liquid behavior for x>0.2 with weak correlations. There is a continuous change in Yb valence from nearly trivalent at low x to a slightly lower value for x=0.6, which correlates with the Kondo temperature. Interestingly, specific heat measurements at very low temperatures show that C/T strongly increases toward lower T for x=0.13 and x=0.2 with a very similar power law. This suggests that in YbNi4(P1-xAsx)2 a quantum critical line rather than a quantum critical point might exist. © 2025 American Physical Society.
