Orientation of the ground-state orbital in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>CeCoIn</mml:mi><mml:mn>5</mml:mn></mml:msub></mml:math>and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>CeRhIn</mml:mi><mml:mn>5</mml:mn></mml:msub></mml:math>

Sundermann, Martin; Amorese, Andrea; Strigari, F.; Leedahl, Brett; Tjeng, L. H.; Haverkort, M. W.; Gretarsson, H.; Yavaş, Hasan; Sala, M. Moretti; Bauer, E. D.; Rosa, P. F. S.; Thompson, J. D.; Severing, A.

doi:10.1103/physrevb.99.235143

Cited by 14 publications

(7 citation statements)

References 41 publications

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“…The persistent observation of a ZBCP in all (110) junctions suggests that the Kondo resonant tunneling off the localized Ce 4f 1 moments is enhanced in this direction compared to other directions. This is in agreement with a recent report [59] that the lobe direction of the ground state 4f orbital in CeCoIn 5 is [110]. The ZBCPs observed in some non-nodal junctions (e.g., Fig.…”

supporting

confidence: 93%

“…If this two-channel screening occurs cooperatively, the conduction electrons are effectively paired via the Kondo effect, leading to a composite pair. Here, the twofold degeneracy of the crystal-field-split ground state Kramers doublet [59] is crucial, as it is for the singlechannel Kondo effect. It is expected that, with the application of a magnetic field, the degeneracy is gradually lifted due to the Zeeman splitting, ultimately suppressing the composite pair formation.…”

Section: Direct Involvement Of Local Moments In the Pairing Processmentioning

confidence: 99%

“…For a full account of the FIG, it is desirable to formulate a more microscopic model that explains, both qualitatively and quantitatively, how the magnetic field suppresses such pairing that directly involves the localized f -moments. Such model would also take into account the exact ground state for the Ce 4f 1 electron in CeCoIn 5 as it has been recently identified to be a Kramer's doublet, that is,  7-= |±5/2˃ + | ∓3/2˃, arising from the crystal-electric field effect [59].…”

Section: Direct Involvement Of Local Moments In the Pairing Processmentioning

confidence: 99%

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Spectroscopic evidence for the direct involvement of local moments in the pairing process of the heavy-fermion superconductor CeCoIn5

et al. 2021

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The microscopic mechanism for electron pairing in heavy-fermion superconductors remains a major challenge in quantum materials. Some form of magnetic mediation is widely accepted with spin fluctuations as a prime candidate. A novel mechanism, "composite pairing" based on the cooperative two-channel Kondo effect directly involving the f-electron moments has also been proposed for some heavy fermion compounds including CeCoIn 5 . The origin of the spin resonance peak observed in neutron scattering measurements on CeCoIn 5 is still controversial and the corresponding hump-dip structure in the tunneling conductance is missing. This is in contrast to the cuprate and Fe-based high-temperature superconductors, where both characteristic signatures are observed, indicating spin fluctuations are likely involved in the pairing process. Here, we report results from planar tunneling spectroscopy along three major crystallographic orientations of CeCoIn 5 over wide ranges of temperature and magnetic field. The pairing gap opens at T p ~ 5 K, well above the bulk T c = 2.3 K, and its directional dependence is consistent with d x2-y2 symmetry. With increasing magnetic field, this pairing gap is suppressed as expected but, intriguingly, a gaplike structure emerges smoothly, increasing linearly up to the highest field applied. This field-induced gaplike feature is only observed below T p . The concomitant appearance of the pairing gap and the fieldinduced gaplike feature, along with its linear increase with field, indicates that the f-electron local moments are directly involved in the pairing process in CeCoIn 5 .

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supporting

confidence: 93%

Section: Direct Involvement Of Local Moments In the Pairing Processmentioning

confidence: 99%

Section: Direct Involvement Of Local Moments In the Pairing Processmentioning

confidence: 99%

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Spectroscopic evidence for the direct involvement of local moments in the pairing process of the heavy-fermion superconductor CeCoIn5

et al. 2021

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“…The CF ground state, in turn, must be of Γ 7 symmetry (if Γ 6 would be the ground state, Γ 7 → Γ 7 CF transition could not be observed.). The assignment of a Γ 7 ground state and a Γ 7 excited state at 70 cm −1 is consistent with previous neutron and X-ray measurements [9,26,27]. The Γ 7 → Γ 6 transition has a frequency of 200 cm −1 determined by inelastic neutron scattering [9,26], but this mode is not resolved in the Raman spectra.…”

Section: Electronic Excitationssupporting

confidence: 88%

Anisotropy of Kondo-lattice coherence in momentum space for CeCoIn5

Ye¹,

Kung²,

Rosa³

et al. 2022

Preprint

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We study the electronic and phononic excitations of heavy-fermion metal CeCoIn5 by polarizationresolved Raman spectroscopy to explore the Kondo-lattice coherence. Below the coherence temperature T* = 45 K, the continuum of electronic excitations in the XY scattering geometry is suppressed at frequencies below 50 cm −1 , whereas the low-frequency continuum in the X'Y' geometry exhibits no change across T*. We relate the suppression to the reduced electron-electron scattering rate resulting from the coherence effect. The presence of suppression in the XY geometry and absence of it in the X'Y' geometry implies that the α and β bands become coherent below T*, whereas the γ band remains largely incoherent down to 10 K. Moreover, two optical phonon modes exhibit anomalies in their temperature dependence of the frequency and linewidth below T*, which results from developing coherent spectral weight near the Fermi level and reduced electron-phonon scattering rate. Our results further support the key role of anisotropic hybridization in CeCoIn5.

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“…(10). Experimentally, the wavefunction of the CF ground state could be determined by core-level non-resonant inelastic X-ray scattering, which has been used for Ce-based heavy fermion systems [42].…”

Section: Angular Electron-cloud Distribution Of the Crystal-field Statesmentioning

confidence: 99%

Lattice dynamics, crystal-field excitations, and quadrupolar fluctuations of YbRu2Ge2

Rosenberg

Fisher

et al. 2019

Phys. Rev. B

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We employ polarization resolved Raman scattering spectroscopy to study ferroquadrupolar (FQ) fluctuations and crystal-field (CF) excitations in YbRu2Ge2 heavy-fermion metal with FQ transition at TQ=10 K. We demonstrate that the electronic static Raman susceptibilities in quadrupolar symmetry channels exhibit nearly Curie law behavior, and that the electron-lattice coupling is essential for the FQ transition at TQ. We establish the CF level scheme of the Yb 3+ ground state 2 F 7/2 multiplet. We study the lattice dynamics and demonstrate coupling between CF transitions and phonon modes. arXiv:1902.02863v2 [cond-mat.str-el]

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Orientation of the ground-state orbital inCeCoIn5andCeRhIn5

Cited by 14 publications

References 41 publications

Spectroscopic evidence for the direct involvement of local moments in the pairing process of the heavy-fermion superconductor CeCoIn5

Spectroscopic evidence for the direct involvement of local moments in the pairing process of the heavy-fermion superconductor CeCoIn5

Anisotropy of Kondo-lattice coherence in momentum space for CeCoIn5

Lattice dynamics, crystal-field excitations, and quadrupolar fluctuations of YbRu2Ge2

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