Evidence for non-Fermi liquid behavior in the Kondo alloy Y_{1-x}U_{x}Pd_{3}

Non-Fermi Liquid Regimes and Superconductivity in the Low Temperature Phase Diagrams of Strongly Correlated d- and f-Electron Materials

“…In performing such an analysis, it is most meaningful that it be performed on cubic materials if they are in the form of polycrystals; if the compounds are not cubic, it is preferable to work with single crystal specimens, if possible, to avoid obtaining a polycrystalline average over the different grains with varying orientations with respect to the current direction in the specimen. One of the most striking types of NFL behavior, which is nearly universal, is found in the specific heat C(T ), which can generally be described by a logarithmic or weak power law divergence in temperature T with decreasing T of C(T )/T [1,2,6,7,35]. In some cases, this behavior crosses over into a more rapid divergence with decreasing T .…”

“…An experimental investigation of the Y 1−x U x Pd 3 system, carried out in our laboratory in 1990, revealed an unconventional Kondo effect with concomitant NFL behavior at low temperatures for U concentrations x in the range 0 < x ≤ 0.2 [6,48]. The NFL characteristics included a linear T -dependence of ρ, a logarithmic in T divergence of C/T , and a non-Curie Weiss χ that varies as T 1/2 .…”

“…As a result, it is difficult to determine whether the magnetization with negative curvature sometimes found for NFL systems is intrinsic or associated with contributions from magnetic impurities. This yields uncertainties in how to analyze the magnetization measurements; i.e., whether to determine χ(T ) from the low field susceptibility or correct the magnetization for the possible presence of magnetic impurities as described in other publications [6,36].…”

“…In many cases, the power law dependence can extend over several decades in temperature. A common method of analyzing the resistivity is to plot the ρ(T ) data as ln[ρ(T ) − ρ 0 ] vs. ln T and to adjust ρ 0 to give the best fit of the data by a straight line over the largest range of temperature with emphasis on the data at the lowest temperatures [6]. Such a straight line has the form ln[ρ(T ) − ρ 0 ] = ln A + n ln T , from which ρ 0 , A and n can be determined.…”

“…The NFL behavior is characterized by logarithmic or weak power law divergences in the physical properties at low temperatures T and an effective Fermi temperature that appears in the dynamical susceptibility that is the temperature T itself (i.e., ω/T scaling). The NFL behavior was first established in chemically substituted f -electron compounds containing nonmagnetic substituents [1,6,7] and subsequently observed in stoichiometric f -electron compounds [8,9]. Since these NFL characteristics are found in both chemically substituted and stoichiometric compounds, the underlying physics does not seem to be primarily driven by atomic disorder.…”