Dielectric function of YBa2Cu3O7-? between 50 meV and 50 eV

Romberg, H.; Nücker, N.; Fink, J.; Wolf, Th.; Xi, X. X.; Koch, B.; Geserich, H. P.; Dürrler, M.; Aßmus, W.; Gegenheimer, B.

doi:10.1007/bf01313317

Cited by 84 publications

(49 citation statements)

References 67 publications

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“…When the plasmon is strongly damped (usually due to an interaction with single-particle excitations), the zero-crossing disappears but a relict may remain as a minimum of Re(ε). Here we find no zerocrossings of Re(ε) in agreement with earlier studies, 12 implying that the plasmons in this system are heavily damped. While the peaks A-C are produced by dips in the real part at low q, they change their character into a peak in the imaginary part at highest q studied here, showing a transition from a highly-damped plasmon to a single-particle excitation as q is increased.…”

Section: 35supporting

confidence: 93%

“…For example, an early EELS study of YBCO has revealed spectra equivalent to those reported here at the lowest q (Ref. 12). The anisotropy between the ab plane and the c-axis results is surprisingly small in the experiment.…”

Section: 35supporting

confidence: 62%

“…5-7) has already been used to study such systems but these experiments do not probe the dielectric function and should not be confused with non-resonant IXS which we use here. In particular on YBCO, EELS experiments [8][9][10][11][12] were performed soon after the discovery of its superconductivity, but there are no existing IXS experiments. This work is an attempt to close the gap in our accessible kinematic probing range of excitation energies and momenta.…”

Section: Introductionmentioning

confidence: 99%

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Screening inYBa2Cu3O7−δat large wave vectors

et al. 2010

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We present experimental inelastic x-ray scattering (IXS) and ab initio time-dependent densityfunctional-theory (TDDFT) studies of YBa2Cu3O 7−δ . The response of the low-lying Ba 5p and Y 4p core electrons is shown to interact strongly with the Cu 3d and O 2p excitations, with important consequences on screening. The agreement between IXS and TDDFT results is excellent, apart from a new type of excitations, mainly related to loosely bound Ba electrons and significantly affected by correlations. This points to correlation mechanisms not fully described by TDDFT that might have a role in giving rise to antiscreening.

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Section: 35supporting

confidence: 93%

Section: 35supporting

confidence: 62%

Section: Introductionmentioning

confidence: 99%

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Screening inYBa2Cu3O7−δat large wave vectors

et al. 2010

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“…Furthermore, it allows momentum dependent measurements of the loss function, i. e. the observation of non-vertical transitions within the band structure of a solid, the idendification of dipole forbidden excitations [22,23] and the determination of the dispersion of excitons, interband transitions or charge carrier plasmons. [24][25][26][27][28] As the dispersion of a charge carrier plasmon is related to the Fermi velocity, EELS studies also provide valuable insights into further fundamental electronic parameters.…”

Section: Introductionmentioning

confidence: 99%

Plasmons and interband transitions ofCa11Sr3Cu24O41
Roth
¹
,
Heß
²
,
Büchner
³

et al. 2010
Phys. Rev. B
9
1
8
0
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Electron energy-loss spectroscopy studies have been performed in order to get a deeper insight into the electronic structure and elementary excitations of the two -leg ladder system Ca 11 Sr 3 Cu 24 O 41 . We find a strong anisotropy of the loss function for momentum transfers along the a and c -crystallographic axis, and a remarkable linear plasmon dispersion for a momentum transfer parallel to the legs of the ladders. The investigated spectral features are attributed to localized and delocalized charge-transfer excitations and the charge carrier plasmon. The charge carrier plasmon position and dispersion in the long wave-length limit agree well with expectations based upon the band structure of the two-leg ladder, while the observed quasi-linear plasmon dispersion might be related to the peculiar properties of underdoped cuprates in general.

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“…2 to investigate the sources of error arising from the low frequency extrapolations. The reflectance was extended to high-frequency (between 40 000 and 350 000 cm −1 ) using data from Romberg et al [35]. Free-electron behavior (R ∝ ω −4 ) was assumed to hold at higher frequencies.…”

mentioning

confidence: 99%

a-axis optical conductivity of detwinned ortho-IIYBa2Cu3O6.50
Hwang
¹
,
Yang
²
,
Timusk
³

et al. 2006
Phys. Rev. B
93
21
148
0
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The a-axis optical properties of a detwinned single crystal of YBa2Cu3O6.50 in the ortho II phase (Ortho II Y123, Tc= 59 K) were determined from reflectance data over a wide frequency range (70 -42 000 cm −1 ) for nine temperature values between 28 and 295 K. Above 200 K the spectra are dominated by a broad background of scattering that extends to 1 eV. Below 200 K a shoulder in the reflectance appears and signals the onset of scattering at 400 cm −1 . In this temperature range we also observe a peak in the optical conductivity at 177 cm −1 . Below 59 K, the superconducting transition temperature, the spectra change dramatically with the appearance of the superconducting condensate. Its spectral weight is consistent, to within experimental error, with the Ferrell-GloverTinkham (FGT) sum rule. We also compare our data with magnetic neutron scattering on samples from the same source that show a strong resonance at 31 meV. We find that the scattering rates can be modeled as the combined effect of the neutron resonance and a bosonic background in the presence of a density of states with a pseudogap. The model shows that the decreasing amplitude of the neutron resonance with temperature is compensated for by an increasing of the bosonic background yielding a net temperature independent scattering rate at high frequencies. This is in agreement with the experiments. The complete phase diagram of the high temperature superconducting (HTSC) cuprates is still under intense debate. The normal state, particularly in the underdoped region, is dominated by a variety of not-well-understood cross-over phenomena that may either be precursors to superconductivity or competing states. These include the pseudogap [1], the magnetic resonance [2,3,4], the anomalous Nernst effect [5,6], stripe order [7,8,9,10] and possible superconducting fluctuations [11,12]. The situation is further complicated by the presence of disorder and the practical considerations that lead to a situation where a given cuprate is not investigated with all the available experimental techniques. Ideally, one would like to have a system where disorder is minimized and several experimental techniques can be used with the same crystals. As a step in that direction we present detailed a-axis optical data on the highly ordered ortho-II phase of YBa 2 Cu 3 O 6.50 (Ortho II Y123) and compare these data with recent results from magnetic neutron scattering and microwave spectroscopy on crystals from the same source.An important motivation for a comparison between transport properties and the magnetic neutron resonance comes from the observation that the carrier life time, as measured by infrared spectroscopy, is dominated by a bosonic mode [13,14,15,16,17] whose frequency and intensity, as a function of temperature and doping level, tracks the inelastic magnetic resonance at 41 meV with in-plane momentum transfer of (π, π) [15,16]. The magnetic resonance has also been invoked to explain other self-energy effects such as the kink in the dispersion of angle-resolved photo...

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Dielectric function of YBa2Cu3O7-? between 50 meV and 50 eV

Cited by 84 publications

References 67 publications

Screening inYBa2Cu3O7−δat large wave vectors

Screening inYBa2Cu3O7−δat large wave vectors

Plasmons and interband transitions ofCa11Sr3Cu24O41
Roth
¹
,
Heß
²
,
Büchner
³

et al. 2010
Phys. Rev. B
9
1
8
0
View full text Add to dashboard Cite

a-axis optical conductivity of detwinned ortho-IIYBa2Cu3O6.50
Hwang
¹
,
Yang
²
,
Timusk
³

et al. 2006
Phys. Rev. B
93
21
148
0
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Dielectric function of YBa2Cu3O7-? between 50 meV and 50 eV

Cited by 84 publications

References 67 publications

Screening inYBa2Cu3O7−δat large wave vectors

Screening inYBa2Cu3O7−δat large wave vectors

Plasmons and interband transitions ofCa11Sr3Cu24O41Roth1, Heß2, Büchner3 et al. 2010Phys. Rev. B9180View full textAdd to dashboardCite

a-axis optical conductivity of detwinned ortho-IIYBa2Cu3O6.50Hwang1, Yang2, Timusk3 et al. 2006Phys. Rev. B93211480View full textAdd to dashboardCite

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Plasmons and interband transitions ofCa11Sr3Cu24O41
Roth
¹
,
Heß
²
,
Büchner
³

et al. 2010
Phys. Rev. B
9
1
8
0
View full text Add to dashboard Cite

a-axis optical conductivity of detwinned ortho-IIYBa2Cu3O6.50
Hwang
¹
,
Yang
²
,
Timusk
³

et al. 2006
Phys. Rev. B
93
21
148
0
View full text Add to dashboard Cite