Metallurgical and low-temperature electronic properties ofM1−xUxPd<

Abstract

In this paper, we compare the metallurgical and low-temperature electronic properties of the pseudo-binary alloy systems Sc 1Ϫx U x Pd 3 and Y 1Ϫx U x Pd 3 to gain insight into the nature of the non-Fermi-liquid ͑NFL͒ behavior observed in these systems at low temperatures. Our results show that both the Sc 1Ϫx U x Pd 3 and Y 1Ϫx U x Pd 3 systems exhibit similar NFL behavior, in spite of significant differences in their metallurgical properties. This comparison provides strong evidence that the NFL behavior is an intrinsic property, and not an extrinsic property driven by metallurgical disorder. Scanning electron microscopy and x-ray-diffraction measurements revealed that the U in the Y 1Ϫx U x Pd 3 system is inhomogeneously distributed on the micron length scale, while the U in the Sc 1Ϫx U x Pd 3 system is nearly homogeneously distributed. However, low-temperature measurements of the electronic specific heat coefficient ␥ϭC p /T, magnetic susceptibility , and electrical resistivity show that the compounds Sc 0.7 U 0.3 Pd 3 and Y 0.8 U 0.2 Pd 3 exhibit the following NFL behavior with nearly the same Kondo temperature (T K ): C p

Non-Fermi liquid behavior and quantum criticality in and

“…Given that Sc and Y are isoelectronic, this similarity may not seem surprising, but it should be noted that La 1Àx U x Pd 3 does not display Kondo or NFL behavior [3,5]. Practically, the significance of the correspondence between the Sc and Y compounds lies in the microscopic compositional inhomogeneity in Y 1Àx U x Pd 3 , which has complicated the interpretation of its physical properties [5,6]. In contrast, Sc 1Àx U x Pd 3 is metallurgically wellbehaved, making it possible to study the same NFL behavior in a homogeneous system [5].…”

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

“…After Refs. [49,52] χ(T ) to lower values of x. This is because the NFL features weaken rapidly with decreasing x since their magnitudes are proportional to x and their gradients decrease with increasing T K (decreasing x).…”

“…Given that Sc and Y are isoelectronic, this similarity may not seem surprising; however, La is also isoelectronic with Sc and Y, but La 1−x U x Pd 3 does not display Kondo or NFL behavior [49,52] [52] There has been some debate about whether the NFL behavior in the Y 1−x U x Pd 3 system is an intrinsic electronic property or an extrinsic effect associated with metallurgical inhomogeneity that several groups have reported is present in their samples of Y 1−x U x Pd 3 [59,60]. Whereas U is inhomogeneously distributed on a micron length scale in the Y 1−x U x Pd 3 system, U was found to be nearly homogeneously distributed in the Sc 1−x U x Pd 3 system [52]. However, in spite of the difference in their metallurgical properties, the Y 1−x U x Pd 3 and Sc 1−x U x Pd 3 systems have very similar T -x phase diagrams and NFL characteristics in their low temperature physical properties.…”

Transport properties of moderately disorderedUCu4Pd

“…Specifically, for URh 2 Ge 2 it has been shown that by varying the level of crystallographic disorder a transition from an antiferromagnetic to a spin glass ground state can be facilitated 22 . Further, in the alloying series U(Cu,Pd) 5 and (Y,U)Pd 3 spin glass ground states are suppressed to zero temperature, and are associated with NFL characteristics 13,19 . Consequently, if glassy states occur in a given class of compounds, we expect a behavior as sketched in Fig.…”

“…Here, in particular, studies have been performed on pseudo-binary cerium or uranium intermetallics with stoichiometries (Ce,U):T (T = intermetallic element) of 1:1, 1:2 or 1:3 10,11,12,13 , or ternary uranium heavy fermions like those of composition 2:1:3 14,15,16,17 , the U(Cu,Pd) 5 system 18,19,20,21 , or U-and Ce-122 compounds 22,23,24,25,26 . The goal of such material studies is the search for quantum critical behavior close to a magnetic instability, which might be accessed by tuning a magnetic transition temperature to zero through alloying.…”