Electron-phonon interaction in the lamellar cobaltate<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mi>Na</mml:mi><mml:mi>x</mml:mi></mml:msub><mml:msub><mml:mi>CoO</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math>

Donkov, A. A.; Korshunov, M. M.; Eremin, I.; Lemmens, P.; Gnezdilov, V. P.; Chou, F. C.; Lin, C. T.

doi:10.1103/physrevb.77.100504

Cited by 14 publications

(22 citation statements)

References 39 publications

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“…2(c) and 3(b), we show the resulting momentum dependence of the phonon frequencies for the A 1g and E 1g phonon modes along the main symmetry points of the first BZ. The largest softening of the A 1g phonon mode arises around the Γ point as we have already previously noticed [13]. At the same time, we find that the largest renormalization of the E 1g mode is around the M point of the BZ.…”

Section: Electron-phonon Interactionsupporting

confidence: 64%

“…The situation is opposite for the A 1g phonon mode: the largest coupling to the conduction electrons occur in this case around the Γ point of he first BZ. This explains the doping dependence of the A 1g phonon mode (and the doping independence of the E 1g mode) observed in Raman experiments where q = 0 point is probed [13].…”

Section: Electron-phonon Interactionmentioning

confidence: 61%

“…This work compliments our previous study [13]. In particular, we concentrate on the two oxygen phonon modes with A 1g and E 1g symmetries, which were found in Raman experiments.…”

Section: Introductionmentioning

confidence: 64%

“…Previously, to find the renormalization of the bare phonon frequency and to compare the results to the Raman experiments we set q → 0 limit and solved (5) numerically as a function of the doping concentration [13]. The main contribution to the renormalization of the optical phonon modes in Raman experiments comes from the interband transi-tions, i.e., terms with g α =β kq while intraband transitions have been neglected.…”

Section: Electron-phonon Interactionmentioning

confidence: 99%

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Electron–Phonon Interaction and Phonon Renormalization in the Lamellar Cobaltate Na x CoO2

Donkov

Eremin

Knolle

et al. 2008

J Supercond Nov Magn

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We study theoretically the electron-phonon interaction in Na x CoO 2 . For the A 1g and E 1g phonon modes found in Raman experiments, we calculate the matrix elements of the electron-phonon interaction. Analyzing the feedback effect of the conduction electrons on the phonon frequency ω, we investigate the doping dependence of these two phonon modes. Due to the momentum dependence of the electron-phonon interaction, we find the strongest renormalization of the E 1g mode around the Brillouin zone boundary which should be observed in the neutron scattering. At the same time, the A 1g mode shows the strongest coupling to the conducting electrons around the Γ point and reveals its doping dependence in the Raman experiments. Our results shed light on the possible importance of the electron-phonon interaction in the lamellar sodium cobaltates.

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Section: Electron-phonon Interactionsupporting

confidence: 64%

Section: Electron-phonon Interactionmentioning

confidence: 61%

“…This work compliments our previous study [13]. In particular, we concentrate on the two oxygen phonon modes with A 1g and E 1g symmetries, which were found in Raman experiments.…”

Section: Introductionmentioning

confidence: 64%

Section: Electron-phonon Interactionmentioning

confidence: 99%

See 2 more Smart Citations

Electron–Phonon Interaction and Phonon Renormalization in the Lamellar Cobaltate Na x CoO2

Donkov

Eremin

Knolle

et al. 2008

J Supercond Nov Magn

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“…60 In the cobaltates a typical frequency of the phonons with E 1g -symmetry, interacting with the e g -orbitals, is just ≈ 60 meV. 61 Another mechanism mixing the LS and HS states could be the intersite electron hopping within the 90 • Co-O-Co bonds. 32 This results in the spin/orbital correlations between the d-sites, 33,34,36 which are underestimated in the GGA+U approximation.…”

Section: Discussionmentioning

confidence: 99%

Origin of electron disproportionation in metallic sodium cobaltates

et al. 2016

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Recently the unusual metallic state with a substantially non-uniform distribution of a charge and magnetic density in CoO2 planes was found experimentally in the NaxCoO2 compound with x > 0.6. We have investigated an origin of such electron disproportionation in the lamellar sodium cobaltates by calculating the ion states as a function of a strength of the electron correlations in the d(Co)-shells within the GGA+U approximation for the system with a realistic crystal structure. It was found that the nonuniformity of spin and charge densities are induced by an ordering of the sodium cations and enhanced correlations. Two important magnetic states of cobalt lattice competing with each other at realistic values of the correlation parameter were found -low spin hexagons (LS) and higher spin kagome lattice (HS-KSL). In the heterogeneous metallic HS-KSL phase magnetic Co ions form a kagomé structure. In LS phase the kagomé pattern is decomposed into hexagons and Co ions possess minimal values of their spin. Coexistence of these states could explain the emergence of the disproportionation with the peculiar kagomé structure experimentally revealed in previous studies of the cobaltates.

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Anomalous isotope effect in iron-based superconductors

Lin

2019

Sci Rep

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The role of electron-phonon interactions in iron-based superconductor is currently under debate with conflicting experimental reports on the isotope effect. To address this important issue, we employ the renormalization-group method to investigate the competition between electron-electron and electron-phonon interactions in these materials. The renormalization-group analysis shows that the ground state is a phonon-dressed unconventional superconductor: the dominant electronic interactions account for pairing mechanism while electron-phonon interactions are subdominant. Because of the phonon dressing, the isotope effect of the critical temperature can be normal or reversed, depending on whether the retarded intra- or inter-band interactions are altered upon isotope substitutions. The connection between the anomalous isotope effect and the unconventional pairing symmetry is discussed at the end.

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Electron-phonon interaction in the lamellar cobaltateNaxCoO2

Cited by 14 publications

References 39 publications

Electron–Phonon Interaction and Phonon Renormalization in the Lamellar Cobaltate Na x CoO2

Electron–Phonon Interaction and Phonon Renormalization in the Lamellar Cobaltate Na x CoO2

Origin of electron disproportionation in metallic sodium cobaltates

Anomalous isotope effect in iron-based superconductors

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