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Cornelius, Andrew; Lawrence, J. M.; Sarrao, J. L.; Fisk, Z.; Hundley, M. F.; Kwei, G. H.; Thompson, J. D.; Booth, C. H.; Bridges, F.

doi:10.1103/physrevb.56.7993

Cited by 119 publications

(128 citation statements)

References 19 publications

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“…Figure 6d shows that the trend in the x dependence of χ(T = 0) 59 generally agrees with the corresponding trend in the Sommerfeld coefficient γ, implying a Wilson ratio within 10% of the value (R = 8 7 ) expected for a j = 7 2 Anderson impurity 3,43 . Thus the T K values inferred from the susceptibility analysis reasonably represent the effective energy scale relevant to the onset of strong-coupling Kondo physics within the low temperature phase.…”

Section: Results X Dependencesupporting

confidence: 64%

“…2 Coqblin-Schreiffer model 3,42 . Figure 6d shows that the trend in the x dependence of χ(T = 0) 59 generally agrees with the corresponding trend in the Sommerfeld coefficient γ, implying a Wilson ratio within 10% of the value (R = 8 7 ) expected for a j = 7 2 Anderson impurity 3,43 .…”

Section: Results X Dependencementioning

confidence: 99%

“…This model, however, seems insufficient to quantitatively describe the phase transition in YbInCu 4 , as evidenced mainly by the smallness of the volume change at the transition. Some authors 3,17,40 have argued that a quasigap, or region of low density of states, exists in the bare band structure located just above the Fermi level in YbInCu 4 , and is important to the phase transition. This description is qualitative, but addresses the change in carrier density as well as the changes related to Kondo physics.…”

Section: Discussion the Phase Transition Of Ybincu4mentioning

confidence: 99%

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Infrared dynamics ofYbIn1−xAgxCu4: Kondo scaling, sum rules, and temperature dependence

et al. 2006

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We present an infrared/optical study of the dynamics of the strongly correlated electron system YbIn1−xAgxCu4 as a function of doping and temperature for x ranging from 0 to 1, and T between 20 and 300 K. This study reveals information about the unusual phase transition as well as the phases themselves. Scaling relations emerge from the data and are investigated in detail using a periodic Anderson model based calculation. We also provide a picture in which to view both the low and high-energy x -dependent features of the infrared data, including identification of high energy, temperature dependent features.When exploring the complex terrain of correlated electron phases, one is often interested in the phase boundaries separating systems which are controlled by different physics. In the low doping regime (x<0.2) of YbIn 1−x Ag x Cu 4 , a temperature-driven, first-order electronic phase transition separates two phases which are characterized by widely disparate effective energy scales (T K ) associated with the effects of hybridization between the localized Yb f -electrons and the itinerant conduction electrons. This rapid change provides both an opportunity to identify and isolate features associated with many-body hybridization physics and raises fundamental questions regarding the origin of the transition itself.The valence transition in YbInCu 4 has been examined with a variety of experimental techniques 1,2,3,4,5,6,7 , and exhibits some similarities 8,9,10 to phase transitions observed in certain rare-earth intermetallic compounds 11,12 . Samples of high quality can be made, and provide the only known example of a valence transition occurring at ambient pressure in a stoichiometric sample. The synthesis of high quality single crystal samples has allowed the detailed study of the phase diagram of YbIn 1−x Ag x Cu 4 , and continued effort has revealed a tendency of the system to order ferromagnetically as the phase transition temperature is driven to zero either by pressure 13,14 or Y doping 13,15 . The presence of interesting phase competition in a system where the sample chemistry is well controlled enhances our interest in this correlated electron system. Figure 1 shows a schematic representation of the phase diagram of YbIn 1−x Ag x Cu 4 . At low doping, a line of first order phase transitions separates a low temperature, mixed-valent phase and a high temperature local moment phase. In YbInCu 4 (x=0) at high temperature (T > T v = 42 K), the magnetic response exhibits a Curie-Weiss form with magnitude appropriate to j = 7/2 moment of Yb and a small Weiss temperature 16 Θ W ∼ −13 K, which constrains the effective Kondo temperature appropriate in this high temperature range to be comparably small in magnitude. The resistivity in this temperature range 2 is very high for a metal (ρ dc ≃ 150µΩ-cm) and together with Hall measurements indicate a very low (hole) carrier concentration 2 . Lowering the temperature through the first order phase transition has dramatic effects on both the spin and charge response. For...

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Section: Results X Dependencesupporting

confidence: 64%

Section: Results X Dependencementioning

confidence: 99%

Section: Discussion the Phase Transition Of Ybincu4mentioning

confidence: 99%

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Infrared dynamics ofYbIn1−xAgxCu4: Kondo scaling, sum rules, and temperature dependence

et al. 2006

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“…In YbInCu 4 , isostructural FOVT is also known to occur [71]. As temperature decreases, the Yb valence shows a discontinuous change from Yb +2.97 to Yb +2.84 with a volume expansion, i.e., 0.5% increase in the unit-cell volume, at T v = 42 K [73,74,75,76]. Hence, in the valence crossover regime where most of Ce-and Yb-based heavy fermion systems are considered to be located, the valence change is expected to be in the order of 0.01, even when sharp valence crossover occurs (see Fig.…”

Section: Discussionmentioning

confidence: 99%

New universality class of quantum criticality in Ce- and Yb-based heavy fermions

Watanabe¹,

Miyake²

2012

J. Phys.: Condens. Matter

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Abstract.A new universality class of quantum criticality emerging in itinerant electron systems with strong local electron correlations is discussed. The quantum criticality of a Ce-or Yb-valence transition gives us a unified explanation for unconventional criticality commonly observed in heavy fermion metals such as YbRh 2 Si 2 and β-YbAlB 4 , YbCu 5−x Al x , and CeIrIn 5 . The key origin is due to the locality of the critical valence fluctuation mode emerging near the quantum critical end point of the first-order valence transition, which is caused by strong electron correlations for f electrons. Wider relevance of this new criticality and important future measurements to uncover its origin are also discussed.

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“…For example, YbMgCu 4 has n f = 0.69, 36 and the low temperature state of YbInCu 4 has n f = 0.83. 37 As an order of magnitude estimate of the Kondo temperature, T K , we note that:…”

Section: Discussionmentioning

confidence: 99%