Crossover from a heavy fermion to intermediate valence state in noncentrosymmetric Yb2Ni12(P,As)7

Abstract

We report measurements of the physical properties and electronic structure of the hexagonal compounds Yb2Ni12Pn7 (Pn = P, As) by measuring the electrical resistivity, magnetization, specific heat and partial fluorescence yield x-ray absorption spectroscopy (PFY-XAS). These demonstrate a crossover upon reducing the unit cell volume, from an intermediate valence state in Yb2Ni12As7 to a heavy-fermion paramagnetic state in Yb2Ni12P7, where the Yb is nearly trivalent. Application of pressure to Yb2Ni12P7 suppresses T_FL, the temperature below which Fermi liquid behavior is recovered, suggesting the presence of a quantum critical point (QCP) under pressure. However, while there is little change in the Yb valence of Yb2Ni12P7 up to 30 GPa, there is a strong increase for Yb2Ni12As7 under pressure, before a near constant value is reached. These results indicate that any magnetic QCP in this system is well separated from strong valence fluctuations. The pressure dependence of the valence and lattice parameters of Yb2Ni12As7 are compared and at 1 GPa, there is an anomaly in the unit cell volume as well as a change in the slope of the Yb valence, indicating a correlation between structural and electronic changes.

11 pages, 9 figures

References in corpus (9)

• Signatures of valence fluctuations in CeCu2Si2 under high pressure
• Quantum Criticality without Tuning in the Mixed Valence Compound beta-YbAlB4
• Universality in heavy-fermion systems with general degeneracy
• Strong valence fluctuation in the quantum critical heavy fermion superconductor beta-YbAlB4: A hard x-ray photoemission study
• Non-Fermi liquid states in the pressurized $CeC{u}_2(S{i}_{1-x}G{e}_x{)}_2$ system: two critical points
• Pressure-Induced Valence Crossover and Novel Metamagnetic Behavior near the Antiferromagnetic Quantum Phase Transition of YbNi${}_3$Ga${}_9$
• Valence Instability of YbCu${}_2$Si${}_2$ through its quantum critical point
• Crossover between Fermi liquid and non-Fermi liquid behavior in the non-centrosymmetric compound Yb${}_2$Ni${}_{12}$P${}_7$
• Transport, magnetic, and thermal properties of non-centrosymmetric Yb2Co12P7

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• Crystal, local atomic and electronic structures of YbFe${}_2$Zn${}_{20-x}$Cd${}_x$ ($0\le x\le 1.4$): a multi-band system with possible coexistence of light and heavy fermions