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Levallois, Julien; Lévy-Bertrand, F.; Tran, Michaël; Stricker, D.; Mydosh, J. A.; Huang, Yingkai; Marel, D. van der

doi:10.1103/physrevb.84.184420

Cited by 42 publications

(75 citation statements)

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“…A slight sharpening seems to appear below 20-30 K, which might be concomitant with the electronic gap opening at T 0 observed by optical conductivity 20,[41][42][43] and Raman scattering 26 .…”

Section: Resultsmentioning

confidence: 99%

Lattice dynamics of the heavy-fermion compoundURu2Si2

et al. 2015

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We report a comprehensive investigation of the lattice dynamics of URu2Si2 as a function of temperature using Raman scattering, optical conductivity and inelastic neutron scattering measurements as well as theoretical ab initio calculations. The main effects on the optical phonon modes are related to Kondo physics. The B1g (Γ3 symmetry) phonon mode slightly softens below ∼100 K, in connection with the previously reported softening of the elastic constant, C11 − C12, of the same symmetry, both observations suggesting a B1g symmetry-breaking instability in the Kondo regime. Through optical conductivity, we detect clear signatures of strong electron-phonon coupling, with temperature dependent spectral weight and Fano line shape of some phonon modes. Surprisingly, the line shapes of two phonon modes, Eu(1) and A2u(2), show opposite temperature dependencies. The A2u(2) mode loses its Fano shape below 150 K, whereas the Eu(1) mode acquires it below 100 K, in the Kondo cross-over regime. This may point out to momentum-dependent Kondo physics. By inelastic neutron scattering measurements, we have drawn the full dispersion of the phonon modes between 300 K and 2 K. No remarkable temperature dependence has been obtained including through the hidden order transition. Ab initio calculations with the spin-orbit coupling are in good agreement with the data except for a few low energy branches with propagation in the (a,b) plane.

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Section: Resultsmentioning

confidence: 99%

Lattice dynamics of the heavy-fermion compoundURu2Si2

et al. 2015

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“…According to Levallois et al [7] there is a break in the rate of change of the Drude plasma frequency at 30 K as well as the scattering rate -both evolve more rapidly below this temperature. But the dc resistivity does not show any discontinuous kinks between 35 K and 17.5 K, only a gradual flattening of the curve as T HO is approached from above, followed by an upturn below the transition.…”

Section: Philmag4mentioning

confidence: 99%

“…This procedure gives b ⇡ 0.9, which is within the margin of error of the experimental value b = 1 ± 0.1. 7 The behavior of 1/⌧ (⌦, T ) in the Ce and Nd compounds (Refs. 8 and 9, correspondingly) is qualitatively similar to that in URu 2 Si 2 , although the ranges of ⌦ and T are drastically di↵erent.…”

Section: Philmag4mentioning

confidence: 99%

“…The spectral weight lost in the gap was transferred to frequencies just above the gap, typical of a density wave transition. Subsequent optical work has centred around investigations of the effects of doping on the hidden order [5,6], of the effect of hybridization on the electrodynamics [7][8][9][10] and the anisotropy of the hidden order parameter [11]. The superconducting state occurs below the temperatures available in typical optical experiments; likewise, the large moment antiferromagnet state (LM-AFM) induced by hydrostatic pressure has not yet been investigated optically.…”

Section: Introductionmentioning

confidence: 99%

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Optical study of hybridization and hidden order in URu₂Si₂

Hall

Timusk

2014

Philosophical Magazine

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We summarize existing optical data of URu 2 Si 2 to clarify the nature of the hidden order transition in this heavy fermion metal. Hybridization develops between 50 K and 17.5 K, and a coherent Drude peak emerges which mirrors the changes in the dc resistivity. The Drude weight indicates that there is little change in the effective mass of these carriers in this temperature range. In addition, there is a flat background conductivity that develops a partial hybridization gap at 10 meV as the temperature is lowered, shifting spectral weight to higher frequencies above 300 meV. Below 30 K the carriers become increasingly coherent and Fermi-liquid-like as the hidden order transition is approached. The hidden order state in URu 2 Si 2 is characterized by multiple anisotropic gaps. The gap parameter ∆a = 3.2 meV in the ab-plane. In the c-direction, there are two distinct gaps with magnitudes of ∆ c1 = 2.7 meV and ∆ c2 = 1.8 meV. These observations are in good agreement with other spectroscopic measurements. Overall, the spectrum can be fit by a Dynes-type density of states model to extract values of the hidden order gap. The transfer of spectral weight strongly resembles what one sees in density wave transitions.

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“…Another experimental technique brought to bear on the HO symmetry breaking and putative domain formation was 29 Si nuclear magnetic resonance (NMR). The JAEA-Tokai group [20] using 29 Si spectra measured the Knight shift and the NMR linewidth with basal-plane field rotation over angle θ, both above and below T 0 .…”

Section: Controversial Experiments and Theorymentioning

confidence: 99%

Hidden order behaviour in URu₂Si₂(A critical review of the status of hidden order in 2014)

Mydosh

Oppeneer

2014

Philosophical Magazine

117

108

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Throughout the past three decades the hidden order (HO) problem in URu 2 Si 2 has remained a "hot topic" in the physics of strongly correlated electron systems with well over 600 publications related to this subject. Presently in 2014 there has been significant progress in combining various experimental results embedded within electronic structure calculations using density functional theory (DFT) to give a consistent description of the itinerant behaviour of the HO transition and its low temperature state. Here we review six different experiments: ARPES, quantum oscillations, neutron scattering, RXD, optical spectroscopy and STM/STS. We then establish the consistencies among these experiments when viewed through the Fermi-surface nesting, folding and gapping framework as predicted by DFT. We also discuss a group of other experiments (torque, cyclotron resonance, NMR and XRD) that are more controversial and are presently in a "transition" state regarding their interpretation as rotational symmetry breaking and dotriacontapole formation. There are also a series of recent "exotic" experiments (Raman scattering, polar Kerr effect and ultrasonics) that require verification, yet they offer new insights into the HO symmetry breaking and order parameter. We conclude with some constraining comments on the microscopic models that rely on localised 5f -U states and strong Ising anisotropy for explaining the HO transition, and with an examination of different models in the light of recent experiments.

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Hybridization gap and anisotropic far-infrared optical conductivity of URu2Si2

Cited by 42 publications

References 47 publications

Lattice dynamics of the heavy-fermion compoundURu2Si2

Lattice dynamics of the heavy-fermion compoundURu2Si2

Optical study of hybridization and hidden order in URu₂Si₂

Hidden order behaviour in URu₂Si₂(A critical review of the status of hidden order in 2014)

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Hybridization gap and anisotropic far-infrared optical conductivity of URu2Si2

Cited by 42 publications

References 47 publications

Lattice dynamics of the heavy-fermion compoundURu2Si2

Lattice dynamics of the heavy-fermion compoundURu2Si2

Optical study of hybridization and hidden order in URu2Si2

Hidden order behaviour in URu2Si2(A critical review of the status of hidden order in 2014)

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Product

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Optical study of hybridization and hidden order in URu₂Si₂

Hidden order behaviour in URu₂Si₂(A critical review of the status of hidden order in 2014)