Suppression of f-Electron Itinerancy in CeRu2Si2 by a Strong Magnetic Field

Abstract

The valence state of Ce in a canonical heavy fermion compound CeRu2Si2 has been investigated by synchrotron X-ray absorption spectroscopy at 1.8 K in high magnetic fields of up to 40 T. The valence was slightly larger than for the pure trivalent state (Ce3+: f1), as expected in heavy fermion compounds, and it decreased toward the trivalent state as the magnetic field was increased. The field-induced valence reduction indicates that the itinerant character of the 4f electrons in CeRu2Si2 was suppressed by a strong magnetic field. The suppression was gradual and showed characteristic magnetic field dependence, which reflects the metamagnetism around Hm \sim 8 T. The itinerant character persisted, even at 40 T (\sim 5Hm), suggesting that the Kondo bound state is continuously broken by magnetic fields and that it should completely collapse at fields exceeding 200 T.

5 pages, 4 figures, accepted for publication as a Rapid Communication in Physical Review B

References in corpus (6)

• Fermi-liquid instabilities at magnetic quantum phase transitions
• Quantum Criticality in Heavy Fermion Metals
• Quantum Valence Criticality as Origin of Unconventional Critical Phenomena
• Magnetic-Field Control of Quantum Critical Points of Valence Transition
• Electronic structures of CeRu${}_2{X}_2$ ($X$ = Si, Ge) in the paramagnetic phase studied by soft X-ray ARPES and hard X-ray photoelectron spectroscopy
• Valence Fluctuations Revealed by Magnetic Field Scan: Comparison with Experiments in YbXCu_4 (X=In, Ag, Cd) and CeYIn_5 (Y=Ir, Rh)

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• Unconventional magnetism of the Kondo lattice
• Anomalous ferromagnetism and non-Fermi-liquid behavior in the Kondo lattice CeRuSi2
• Unveiling the double-peak structure of quantum oscillations in the specific heat
• Field-induced valence fluctuation in YbB${}_{12}$
• Magnetic Field Driven Electronic Singularities through Metamagnetic Phenomena: Case of the Heavy Fermion Antiferromagnet Ce(Ru0.92Rh0.08)2Si2
• Quantum oscillations in the heat capacity of Kondo insulator YbB12
• New Methods for Critical Analysis: Revealing the Simultaneous Existence of Universality Classes in Nontrivial Magnetic Systems