Heavy Fermion Scaling: Uranium versus Cerium and Ytterbium Compounds

Journal Article · Sat Jan 01 04:00:00 EST 2011 · Journal of Physics Conference Series

DOI:https://doi.org/10.1088/0953-8984/23/9/094210· OSTI ID:1005193

Lawrence, J. M. ^[1]; Wang, Cuihuan ^[2]; Christianson, Andrew D ^[2]; Bauer, E. D. ^[3]

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1. University of California, Irvine
2. ORNL
3. Los Alamos National Laboratory (LANL)

In an effort to explore the differences between rare-earth-based and uranium-based heavy fermion (HF) compounds that reflect the underlying difference between local 4f moments and itinerant 5f moments we analyze scaling laws that relate the low temperature neutron spectra of the primary ('Kondo-esque') spin fluctuation to the specific heat and susceptibility. While the scaling appears to work very well for the rare earth intermediate valence (IV) compounds, for a number of key uranium compounds the scaling laws fail badly. There are two main reasons for this failure. First, the presence of antiferromagnetic (AF) fluctuations, which contribute significantly to the specific heat, alters the scaling ratios. Second, the scaling laws require knowledge of the high temperature moment degeneracy, which is often undetermined for itinerant 5f electrons. By making plausible corrections for both effects, better scaling ratios are obtained for some uranium compounds. We point out that, while both the uranium HF compounds and the rare earth IV compounds have spin fluctuation characteristic energies of order 5-25 meV, they differ in that the AF fluctuations that are usually seen in the uranium compounds are never seen in the rare earth IV compounds. This suggests that the 5f itineracy increases the f-f exchange relative to the rare earth case.

• Research Organization: Oak Ridge National Laboratory (ORNL); High Flux Isotope Reactor
• Sponsoring Organization: SC USDOE - Office of Science (SC)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1005193
• Journal Information: Journal of Physics Conference Series, Journal Name: Journal of Physics Conference Series Journal Issue: 9 Vol. 23; ISSN 0953-8984
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
CERIUM
ELECTRONS
FERMIONS
FLUCTUATIONS
NEUTRON SPECTRA
RARE EARTHS
SCALING LAWS
SPECIFIC HEAT
SPIN
URANIUM
URANIUM COMPOUNDS
VALENCE
YTTERBIUM COMPOUNDS