Universal low-temperature properties of normal heavy-fermion systems (invited)

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Abstract
We present a microscopic derivation of the Fermi-liquid properties of the Anderson lattice. Our calculations suggest that the low-temperature state of the normal heavy Fermi liquid has a number of universal features, for which there is good experimental evidence. Using the Kondo-boson 1/N expansion, we find the Fermi liquid is characterized by the mean-field ‘‘bare’’ particles (which are heavy) and their respective interactions. The latter are mediated by fluctuations in the f-level position and valence-conduction electron hybridization. Our calculations lead to the following experimental predictions: (i) the low-temperature specific heat behaves as C=γT∝T/TK with corrections ΔC=(T/TK)3 ln(T/TK), (ii) the zero-temperature spin susceptibility χ∝1/TK, and (iii) the resistivity ρ∝(T/TK)2. These results all contain a unique energy scale TK which is proportional to the inverse effective mass. Experimental support for these predictions is provided by evidence of systematic scaling of χ and ρ with γ throughout the entire class of heavy-fermion compounds. In addition we analyze recent pressure-dependent specific-heat measurements on UPt3 combined with χ and ρ data to confirm the scaling of these quantities with a single strongly pressure-dependent energy scale. This analysis provides evidence against current ferromagnetic spin-fluctuation theories.