R. P. Dickey

Evidence for a Common Physical Description of Non-Fermi-Liquid Behavior in Chemically Substituted f -Electron Systems

The non-Fermi-liquid (NFL) behavior observed in the low temperature specific heat C(T) and magnetic susceptibility {chi}(T) of many chemically substituted f -electron systems is analyzed within the context of a recently developed theory based on Griffiths{close_quote} singularities. Measurements of C(T) and {chi}(T) in the systems Th{sub 1{minus}x}U {sub x}Pd{sub 2}Al{sub 3} , Y{sub 1{minus}x}U {sub x}Pd{sub 3} , and UCu{sub 5{minus}x }M{sub x} (M=Pd,thinspPt ) are found to be consistent with C(T)/T{proportional_to}{chi}(T){proportional_to}T{sup {minus}1+{lambda}} predicted by this model with {lambda}{lt}1 in the NFL regime. These results suggest that the NFL properties observed in a wide variety of disordered f -electron systems can be described within the context of a common physical picture. {copyright} {ital 1998} {ital The American Physical Society}

Single-ion scaling of the low-temperature properties of f-electron materials with non-Fermi-liquid groundstates

Certain chemically substituted Ce and U compounds have low-temperature physical properties that exhibit non-Fermi-liquid (NFL) characteristics and apparently constitute a new class of strongly correlated f-electron materials. The NFL behaviour takes the form of weak power law or logarithmic divergences in the temperature dependence of the physical properties that scale with a characteristic temperature T 0 , which, in some systems, can be identified with the Kondo temperature T K . These systems have complex temperature T-chemical substituent composition x phase diagrams, which contain regions displaying the Kondo effect, NFL behaviour, spin glass freezing, magnetic order, quadrupolar order, and, sometimes, even superconductivity. Possible origins of the NFL behaviour include a multichannel Kondo effect and fluctuations of an order parameter in the vicinity of a second-order phase transition at T = 0 K. Recent experiments on the systems Y 1-x U x Pd 3 and U 1-x M x Pd 2 Al 3 (M = Th, Y) are reviewed. In the Y 1-x U x Pd 3 and U 1-x Th x Pd 2 Al 3 systems, the low-temperature physical properties in the NFL regime scale with the U concentration and T K , suggesting that single-ion effects are responsible for the NFL behaviour.

Electronic and magnetic investigation of the filled skutterudite compound CeRu4Sb12

We synthesized the filled skutterudite CeRu4Sb12 in single-crystal form using a molten-metal-flux technique with Sb flux. The specific heat and magnetic susceptibility of CeRu4Sb12 are well described by a logarithmic divergence or a power law in temperature indicating non-Fermi-liquid behaviour at low temperatures. The electrical resistivity is sample dependent with some specimens exhibiting non-Fermi-liquid behaviour below T~5 K in which ρ∝Tn with n~1.4. The application of magnetic fields up to H = 80 kOe does not significantly change the non-Fermi-liquid ground state.

Non-Fermi liquid regimes in the low-temperature phase diagrams of the systems U1−xMxPd2Al3 (M=Y,Th)

Abstract Temperature–composition (T–x) phase diagrams and non-Fermi liquid (NFL) characteristics in the electrical resistivity, specific heat, and magnetic susceptibility at low temperatures for the U1−xMxPd2Al3 (M=Y,Th) systems are described. The T–x phase diagrams, the NFL characteristics, and the underlying mechanisms for the NFL behavior exhibit distinct differences for M=Y3+ and Th4+, apparently reflecting the difference in valence of the M atom substituents, and suggesting that U is tetravalent in these two systems.

Comparison of magnetic and NFL behavior in U1−xMxPd2Al3 (M=La, Y, Th)☆

Abstract The heavy fermion antiferromagnetic superconductor UPd 2 Al 3 displays a number of interesting magnetic and non-Fermi liquid (NFL) ground states when the uranium site is partially occupied by Y, La, or Th. Whereas the magnetic behavior in these systems is determined by valence of the substituent atom, the temperature dependence of the electrical resistivity at low temperatures in the NFL regime correlates with the size of the substituent atom. The phase diagrams, electrical resistivity data, and the lattice parameters of the three systems are compared and contrasted.

Superconductivity in rare earth and actinide compounds

Abstract Rare earth and actinide compounds and the extraordinary superconducting and magnetic phenomena they exhibit are surveyed. The rare earth and actinide compounds described belong to three classes of novel superconducting materials: high temperature, high field superconductors (intermetallics and layered cuprates); superconductors containing localized magnetic moments; heavy fermion superconductors. Recent experiments on the resistive upper critical field of high T c cuprate superconductors and the peak effect in the critical current density of the f-electron superconductor CeRu 2 are discussed.

Magnetism of Pd 1 − x Ni x alloys near the critical concentration for ferromagnetism

We report results of a muon spin rotation and relaxation (

Magnetism of PdNi alloys near the critical concentration for ferromagnetism

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Non-Fermi liquid regimes in U1−xMxPd2Al3(M=Y,Th)

SR) study of dilute Pd

Magnetism ofPd1−xNixalloys near the critical concentration for ferromagnetism

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