Normal-coordinate calculation of the zero-wavevector vibrations of YBa2Cu3O7

Bates, Frances E.; Eldridge, J. E.

doi:10.1016/0038-1098(87)90353-x

Cited by 68 publications

(10 citation statements)

References 13 publications

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“…The broad, weak mode at ≈ 408 cm −1 has been observed in ceramic spectra of samples that appear to have been oxygen reduced [12], but this mode does not correspond to any of the calculated B 1u normal modes [39,40]. A similar mode is seen in YBa 2 Cu 4 O 8 [54] as well as in Pb 2 Sr 2 RCu 3 O 8 [55].…”

Section: The 400 CM −1 Modementioning

confidence: 85%

Optical phonons polarized along the c axis of YBa₂Cu₃O_6+x, for x = 0.5 → 0.95

Homes¹,

Timusk²,

Bonn³

et al. 1995

Can. J. Phys.

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The c-axis polarized phonon spectra of single crystals of YBa2Cu3O6+x, were measured for the doping range x = 0.5 → 0.95, between 10 K and 300 K. The low background electronic conductivity, determined by Kramers-Kronig analysis of the reflectance, leads to a rich phonon structure. With decreased doping the five normally-active B1u modes broaden and the high-frequency apical oxygen mode splits into two components. We associate the higher of these with the two-fold coordinated copper "sticks". The 155 cm −1 low-frequency mode, which involves the apical and the chainoxygens, splits into at least three components with decreasing doping. Some phonon anomalies which occur near Tc in the highly-doped material occur well above Tc in the oxygen-reduced systems. An unusual broad phonon band develops in the normal state at ≈ 400 cm −1 , which becomes more intense at low doping and low temperatures, borrowing oscillator strength from apical and plane oxygen modes resulting in a major transformation of the phonon spectrum below ≈ 150 K.Résumé : Les spectres de phonons polarisés suivant l'axe c, dans des monocristaux de YBa2Cu3O6+x ontété measurés, pour l'intervalle de dopage x = 0, 5à 0, 95, entre 10 et 300 K. La faible condutivitéélectronique de fond, déterminée par analyse Kramers-Kronig de la réflectance, donne lieuà une riche structure de phonons. Lorsqu'on diminue le dopage, les cinque modes B1u normalement actifs s'élargissent, et le mode apicalà haute fréquence de l'oxygène se divise en deux composantes. Nous associons la plus haute de ces composantes aux « bâtons » de cuivreà coordinence deux. Le mode de basse fréquence,à 155 cm −1 , qui implique les oxygènes apical et en chaîne, se sépare en au moins trois composantes lorsque le dopage diminue. Certaines anomalies de phonons, présentes au voisinage de Tc dans les cristaux faiblement dopés, apparaissentà des températures bien plus grandes que Tc dans les systèmes avec moins de l'óxygène. A environ 400 cm −1 , il se développe dans l'état normal une bande large insolite qui devient plus intenseà faible dopage et a basse température, avec une force d'ocsillateur empruntée aux modes apical et plan de l'oxygène, ce quie entraîne une transformation majeure des spectres de phonons au-dessous d'environ 150 K.[Traduit par la rédaction]

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Section: The 400 CM −1 Modementioning

confidence: 85%

Optical phonons polarized along the c axis of YBa₂Cu₃O_6+x, for x = 0.5 → 0.95

Homes¹,

Timusk²,

Bonn³

et al. 1995

Can. J. Phys.

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“…Many calculations of the phonon frequencies have been performed. The different techniques may be classified into three types: force-constant methods, 12,13 shell-model calculations, 14 -16 and ab initio total-energy calculations. 17 -19 Force-constant methods assume massless springs between the atoms and attempt to reproduce the observed spectra by adjusting spring constants for best agreement with experiment.…”

Section: Theoretical Approaches To Vibrations In High-t C Materialsmentioning

confidence: 99%

Vibrational Raman Spectroscopy of High‐temperature Superconductors

Thomsen

Kaczmarczyk

2001

Handbook of Vibrational Spectroscopy

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The sections in this article are Introduction R aman Scattering Theoretical Approaches to Vibrations in High‐ T c Materials Vibrations in High‐ T c Superconductors YBCO and Related Compounds The Bi 2 Sr 2 Ca n − 1 Cu n O 2 n + 4 Superconductor Family Characterization of High‐ T c Materials Foreign Phases Orientation and Oxygen Content Epitaxy Electron–Phonon Interaction Self‐Energy Effects in High‐ T c Superconductors Summary Acknowledgments

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“…Several models of the lattice dynamics of YBa 2 Cu 3 O 7 have been published, 37,28,38,29,32,40 but details of the rather involved calculations have not been given. Despite their usefulness in identifying features in neutron spectra which arise from phonon scattering, such calculations have thus far not been widely employed.…”

Section: Appendix Amentioning

confidence: 99%

“…In our calculations, we adopted the spring constants used by Bates and Eldridge, 37 and then adjusted them so that the kϭ0 eigenvectors fit more closely to the currently available Raman scattering results. 40 Our spring constants are given in Table I.…”

Section: ͑A3͒mentioning

confidence: 99%

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Polarized and unpolarized neutron-scattering study of the dynamical spin susceptibility of YBa2Cu3
Fong
¹
,
Keimer
²
,
Reznik
³

et al. 1996
Phys. Rev. B
146
16
176
1
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We report an extensive study of magnetic excitations in fully oxygenated YBa 2 Cu 3 O 7 , using neutron scattering with and without spin polarization analysis. By calibrating the measured magnetic intensity against calculated structure factors of optical phonons and against antiferromagnetic spin waves measured in the same crystal after deoxygenation to YBa 2 Cu 3 O 6.2 , we establish an absolute intensity scale for the dynamical spin susceptibility, Љ͑q,͒. The integrated spectral weight of the sharp magnetic resonance at បϭ40 meV and q ʈ ϭ(/a,/a) in the superconducting state is ͐d(ប) res Љ (q,)ϭ(0.52Ϯ0.1) at low temperatures. The energy and spectral weight of the resonance are measured up to Tϭ0.8T c . The resonance disappears in the normal state, and a conservative upper limit of 30 states/eV is established for the normal state dynamical susceptibility at q ʈ ϭ(/a,/a) and 10 meVрបр40 meV. Our results are compared to previous neutronscattering data on YBa 2 Cu 3 O 7 , theoretical interpretations of NMR data and current models of the 40 meV resonance.

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Normal-coordinate calculation of the zero-wavevector vibrations of YBa2Cu3O7

Cited by 68 publications

References 13 publications

Optical phonons polarized along the c axis of YBa₂Cu₃O_6+x, for x = 0.5 → 0.95

Optical phonons polarized along the c axis of YBa₂Cu₃O_6+x, for x = 0.5 → 0.95

Vibrational Raman Spectroscopy of High‐temperature Superconductors

Polarized and unpolarized neutron-scattering study of the dynamical spin susceptibility of YBa2Cu3
Fong
¹
,
Keimer
²
,
Reznik
³

et al. 1996
Phys. Rev. B
146
16
176
1
View full text Add to dashboard Cite

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Normal-coordinate calculation of the zero-wavevector vibrations of YBa2Cu3O7

Cited by 68 publications

References 13 publications

Optical phonons polarized along the c axis of YBa2Cu3O6+x, for x = 0.5 → 0.95

Optical phonons polarized along the c axis of YBa2Cu3O6+x, for x = 0.5 → 0.95

Vibrational Raman Spectroscopy of High‐temperature Superconductors

Polarized and unpolarized neutron-scattering study of the dynamical spin susceptibility of YBa2Cu3Fong1, Keimer2, Reznik3 et al. 1996Phys. Rev. B146161761View full textAdd to dashboardCite

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Optical phonons polarized along the c axis of YBa₂Cu₃O_6+x, for x = 0.5 → 0.95

Optical phonons polarized along the c axis of YBa₂Cu₃O_6+x, for x = 0.5 → 0.95

Polarized and unpolarized neutron-scattering study of the dynamical spin susceptibility of YBa2Cu3
Fong
¹
,
Keimer
²
,
Reznik
³

et al. 1996
Phys. Rev. B
146
16
176
1
View full text Add to dashboard Cite