Ground state properties of UNi2Al3 and UPd2Al3

Geibel, C.; Böhn, A.; Caspary, R.; Gloos, K.; Grauel, A.; Hellmann, P.; Modler, R.; Schank, C.; Weber, G.; Steglich, F.

doi:10.1016/0921-4526(93)90531-a

Cited by 59 publications

(12 citation statements)

References 44 publications

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“…Furthermore, such explanation appears in line with the picture that UNi 2 Al 3 has a more pronounced itinerant character than UPd 2 Al 3 . The stronger delocalization of the 5f electrons in UNi 2 Al 3 was notably inferred by the absence of a Curie-Weiss law in the susceptibility (see, for example, Geibel et al, 1993) and the nonobservation of Kondo-like behavior in the electrical resistivity. Hence the substitution of Ni for Pd, which is accompanied by a reduction of the unit-cell volume, increases the hybridization of the f electrons with the conduction electrons, driving the system away from a localized-moments behavior.…”

Section: Fig 19 Crystalline Structure Of Upd 2 Al 3 (And Uni 2 Al 3 )mentioning

confidence: 99%

Heavy-fermion systems studied by μSR technique

1997

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The author attempts to give a comprehensive discussion of studies performed with the positive-muon spin rotation and relaxation technique (also known as the SR technique) on heavy-fermion compounds. The subtle competition between the demagnetizing Kondo interaction and the intersite Ruderman-Kittel-Kasuya-Yosida exchange interaction is believed to be the primary ingredient for the wealth of different ground states observed for this class of rare-earth-and actinide-containing intermetallic compounds. Due to its microscopic character, its sensitivity to extremely small internal fields, and its capacity to detect spatially inhomogeneous magnetic features, the SR technique has been extensively utilized to investigate the peculiar magnetic properties of these ground states and improve our knowledge of heavy-fermion phenomena. In addition to providing a short introduction to SR, where the intrinsic difficulties of the method are clearly stated, this article reviews the main results obtained by this technique on the best-known heavy-fermion compounds (superconductors, band magnets, local-moment magnets, non-Fermi-liquid systems, and Kondo insulators). Special emphasis is placed on the particular information obtainable by monitoring the implanted muon. [S0034-6861(97)00104-9] CONTENTS I. Introduction 1119 A. Puzzle of heavy-fermion physics 1119 B. Tentative classification of heavy-fermion systems 1120 C. Advantages of the SR technique in studying heavy-fermion compounds 1122 D. Organization of the review 1123 II. Overview of the SR Technique 1123 A. Muon production 1124 B. Principle of SR 1124 C. The SR transverse-field (TF) technique

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Section: Fig 19 Crystalline Structure Of Upd 2 Al 3 (And Uni 2 Al 3 )mentioning

confidence: 99%

Heavy-fermion systems studied by μSR technique

1997

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“…Neutron scattering experiments (Geibel et al [176]) established the local moment in UPd2Al3 to be 0.85 B, while that in UNi2Al3 is (Schroeder et al [177]) is much smaller, 0.24 B. These were the first heavy fermion superconductors coexistent with a static local moment.…”

Section: Uni2al3 / Upd2al3mentioning

confidence: 99%

Unconventional superconductivity

Stewart

2017

Advances in Physics

211

165

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Abstract:"Conventional" superconductivity, as used in this review, refers to electron-phonon coupled superconducting electron pairs described by BCS theory. Unconventional superconductivity refers to superconductors where the Cooper pairs are not bound together by phonon-exchange but instead by exchange of some other kind, e. g. spin fluctuations in a superconductor with magnetic order either coexistent or nearby in the phase diagram. Such unconventional superconductivity has been known experimentally since heavy fermion CeCu2Si2, with its strongly correlated 4f electrons, was discovered to superconduct below 0.6 K in 1979. Since the discovery of unconventional superconductivity in the layered cuprates in 1986, the study of these materials saw Tc jump to 164 K by 1994. Further progess in high temperature superconductivity would be aided by understanding the cause of such unconventional pairing. This review compares the fundamental properties of 9 unconventional superconducting classes of materialsfrom 4f-electron heavy fermions to organic superconductors to classes where only three known members exist to the cuprates with over 200 examples -with the hope that common features will emerge to help theory explain (and predict!) these phenomena. In addition, three new emerging classes of superconductors (topological, interfacial -e. g. FeSe on SrTiO3, and H2S under high pressure) are briefly covered, even though their "conventionality" is not yet fully determined.

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“…An important stimulation of interest in physics of the REPd 2 Al 3 compounds provided the discovery of the isostructural heavyfermion superconductors UPd 2 Al 3 ( = 150 mJ K −2 mol −1 , T SC = 2 K, T N = 14 K, and UNi 2 Al 3 [1][2][3]) where superconductivity coexists with quite large antiferromagnetically ordered U moments of 0.85 B (UPd 2 Al 3 ) [1]. All these 123 intermetallics adopt the same hexagonal PrNi 2 Al 3 -type crystal structure [4,5].…”

Section: Introductionmentioning

confidence: 99%