Toward a new microscopic framework for Kondo lattice materials

Lonzarich, G. G.; Pines, David; Yang, Yi-feng

doi:10.1088/1361-6633/80/2/024501

Cited by 31 publications

(34 citation statements)

References 78 publications

(190 reference statements)

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“…We follow Lonzarich et al (13) in making the assumption that, in all three classes, we are dealing with two order parameters (and their associated quantum critical points and fluctuations): an HY order parameter describing the buildup of the emergent heavy electrons and the more familiar AF order parameter describing the buildup of local moment AF order. The magnetic and hybridization quantum critical fluctuations will often not behave independently.…”

Section: Qcps and Their Expected Scaling Signaturesmentioning

confidence: 99%

Quantum critical scaling and fluctuations in Kondo lattice materials

Yang

Pines

Lonzarich

2017

Proc. Natl. Acad. Sci. U.S.A.

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We propose a phenomenological framework for three classes of Kondo lattice materials that incorporates the interplay between the fluctuations associated with the antiferromagnetic quantum critical point and those produced by the hybridization quantum critical point that marks the end of local moment behavior. We show that these fluctuations give rise to two distinct regions of quantum critical scaling: Hybridization fluctuations are responsible for the logarithmic scaling in the density of states of the heavy electron Kondo liquid that emerges below the coherence temperature T * , whereas the unconventional power law scaling in the resistivity that emerges at lower temperatures below T QC may reflect the combined effects of hybridization and antiferromagnetic quantum critical fluctuations. Our framework is supported by experimental measurements on CeCoIn 5 , CeRhIn 5 , and other heavy electron materials.quantum critical behavior | heavy electron | hybridization fluctuations | two fluid H eavy electron materials stand out in the correlated electron family because of the extraordinary variety of quantum mysteries these present. In addition to exhibiting two ordered states at low temperatures, antiferromagnetism and superconductivity, that can coexist, essentially nothing about their highertemperature normal state behavior is what one finds in "normal" materials. Not only does the interaction between a lattice of localized f-electron magnetic moments and background conduction electrons give rise to the emergence, at a temperature T * (often called the coherence temperature), of heavy electrons with masses that can become comparable to that of a muon, but every other aspect of their normal state behavior produced by that interaction is anomalous.Experiments on the best-studied heavy electron material, CeRhIn5, show that, as the temperature and pressure are varied, some five different temperature scales, all well below the crystal field energy levels, are needed to characterize the normal state anomalies depicted in Fig. 1 (1-4): (i)a nuclear magnetic Knight shift that does not follow the measured spin susceptibility below T * ; (ii) a lower limit, TQC , on the ln T universal behavior of the heavy electron density of states that begins at T * ; (iii) a maximum in the magnetic resistivity at T max ρ ; and (iv) a lower limit, T0 or TX depending on the pressure range in which it is studied, on the power law scaling behavior in the resistivity that begins at a temperature, TQC .It is widely believed that the source of these anomalies, and similar ones found in other heavy electron materials, are fluctuations associated with quantum critical points that mark the transition between distinct phases of matter at T = 0. (13) suggesting a path forward for an improved microscopic approach to understanding the emergence of heavy electrons in Kondo lattice materials], these do not explain all of the above anomalies, not least because there is, at present, no microscopic theory of the behavior of the three components (light condu...

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Section: Qcps and Their Expected Scaling Signaturesmentioning

confidence: 99%

Quantum critical scaling and fluctuations in Kondo lattice materials

Yang

Pines

Lonzarich

2017

Proc. Natl. Acad. Sci. U.S.A.

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“…Clearly, this gap is much smaller than the direct hybridization gap (2∆ dir ≈ 75 meV) observed in the FTIR experiments emerging above 100 K [12,29]. Theoretically, these two gaps should be roughly related by [30,31] Then what happens above T * ? Obviously, the absence of the nonlinear effect indicates that the indirect hybridization gap is closed above T * .…”

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confidence: 90%

Hybridization Dynamics in CeCoIn5 Revealed by Ultrafast Optical Spectroscopy

et al. 2020

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We investigate the quasiparticle dynamics in the prototype heavy fermion CeCoIn5 using ultrafast optical pump-probe spectroscopy. Our results indicate that this material system undergoes hybridization fluctuations before full establishment of the heavy electron coherence, as the temperature decreases from ∼120 K (T † ) to ∼55 K (T * ). We reveal that the observed anomalous phonon softening and damping reduction below T * are directly associated with opening of an indirect hybridization gap. We also discover a distinct collective mode with an energy of ∼8 meV below 20 K, which may be the experimental evidence of the predicted unconventional density wave. Our observations provide critical informations for understanding the hybridization dynamics in heavy fermion materials.

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“…of Ce compounds. 17 Note that both Ce-and Yb-based IV metals seem to follow the same universal relation, 10,11 as seen in Fig. 1 compounds.…”

Section: Introductionmentioning

confidence: 66%

“…Nevertheless, it is still true that the mIR peak energy is roughly scaled with √ T K W over many IV metals. [8][9][10][11] Clearly, the characteristics of the mIR peak involve the Kondo physics, and are not due to accidental band structures. Furthermore, effects of momentum-dependent c-f hybridization have been considered in analyzing σ(ω)…”

Section: Introductionmentioning

confidence: 99%

Contrasting pressure evolution of f -electron hybridized states in CeRhIn5 and YbNi3Ga9 : An optical

et al. 2019

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Optical conductivity [σ(ω)] of CeRhIn 5 and YbNi 3 Ga 9 have been measured at external pressures to 10 GPa and at low temperatures to 6 K. Regarding CeRhIn 5 , at ambient pressure the main feature in σ(ω) is a Drude peak due to free carriers. With increasing pressure, however, a characteristic mid-infrared (mIR) peak rapidly develops in σ(ω), and its peak energy and width increase with pressure. These features are consistent with an increased conduction (c)-f electron hybridization at high pressure, and show that the pressure has tuned the electronic state of CeRhIn 5 from very weakly to strongly hybridized ones. As for YbNi 3 Ga 9 , in contrast, a marked mIR peak is observed already at ambient pressure, indicating a strong c-f hybridization. At high pressures, however, the mIR peak shifts to lower energy and becomes diminished, and seems merged with the Drude component at 10 GPa. Namely, CeRhIn 5 and YbNi 3 Ga 9 exhibit some opposite tendencies in the pressure evolutions of σ(ω) and electronic structures. These results are discussed in terms of the pressure evolutions of c-f hybridized electronic states in Ce and Yb compounds, in particular in terms of the electron-hole symmetry often considered between Ce and Yb compounds.

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Toward a new microscopic framework for Kondo lattice materials

Cited by 31 publications

References 78 publications

Quantum critical scaling and fluctuations in Kondo lattice materials

Quantum critical scaling and fluctuations in Kondo lattice materials

Hybridization Dynamics in CeCoIn5 Revealed by Ultrafast Optical Spectroscopy

Contrasting pressure evolution of f -electron hybridized states in CeRhIn5 and YbNi3Ga9 : An optical

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