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Tarascon, Jean‐Marie; Page, Y. Le; Barboux, P.; Bagley, B. G.; Greene, L. H.; McKinnon, W. R.; Hull, G. W.; Giroud, M.; Hwang, D. M.

doi:10.1103/physrevb.37.9382

Cited by 706 publications

(60 citation statements)

References 7 publications

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“…According to experiments [30][31][32][33] , the BSCCO-2212 crystal has a pseudo-tetragonal substructure unit cell, as seen in Figure 2( impurities in adjacent super cell, which allow us to study the effect of the impurity on the first through third nearest neighbor Cu atoms. In the z direction, we use only half of the primitive unit cell ( ) 2 c , because the interaction with the other half is so weak that the omission of it does not affect the surface properties in our test calculations.…”

Section: Computational Detailsmentioning

confidence: 99%

Ab initiocalculation of impurity effects in copper oxide materials

2005

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We describe a method for calculating, within density functional theory, the electronic structure associated with typical defects which substitute for Cu in the CuO 2 planes of high-T c superconducting materials. The focus is primarily on Bi 2 Sr 2 CaCu 2 O 8 , the material on which most STM measurements of impurity resonances in the superconducting state have been performed. The magnitudes of the effective potentials found for Zn, Ni and vacancies on the in-plane Cu sites in this host material are remarkably consistent with phenomenological fits of potential scattering models to STM resonance energies. The effective potential ranges are quite short, of order 1 Å with weak long range tails, in contrast to some current models of extended potentials which attempt to fit STM data.For the case of Zn and Cu vacancies, the effective potentials are strongly repulsive, and states on the impurity site near the Fermi level are simply removed. The local density of states (LDOS) just above the impurity is nevertheless found to be a maximum in the case of Zn and a local minimum in case of the vacancy, in agreement with experiment. The Zn and Cu vacancy patterns are explained as due to the long-range tails of the effective impurity potential at the sample surface. The case of Ni is richer due to the Ni atom's strong hybridization with states near the Fermi level; in particular, the short range part of the potential is attractive, and the LDOS is found to vary rapidly with distance from the surface and from the impurity site. We propose that the current controversy surrounding the observed STM patterns can be resolved by properly accounting for the effective impurity potentials and wave-functions near the cuprate surface. Other aspects of the impurity states for all three species are discussed.2

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Section: Computational Detailsmentioning

confidence: 99%

Ab initiocalculation of impurity effects in copper oxide materials

2005

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“…As a first approximation, a body-centered-tetragonal structure (I4/mmm) has been most frequently used in the interpretation of the IR and Raman spectra of Tl-and Bi-based compounds. According to the x-ray data [27,28], the three Bi-based cuprates of general formula Bi 2 Sr 2 Ca n−1 Cu n O 2n+4+δ with n = 1, 2 and 3 have similar structures of the tetragonal I4/mmm space group (a tetr = 3.814Å), with two formula units (two primitive unit cells) in the crystallographic cell, as illustrated in Figure 1. Primitive unit cells of single, bi-and trilayer Bi-based cuprates differ only in the number (n-1) of CuO 2 -Ca-CuO 2 slabs packed along the c axis; upon insertion of one and two slabs the c axis parameter of the crystallographic cells increases from 24.6 to 30.6, and 37.1Å [28].…”

Section: Introductionmentioning

confidence: 99%

c-axis lattice dynamics in Bi-based cuprate superconductors

et al. 2004

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We present results of a systematic study of the c axis lattice dynamics in single layer Bi 2 Sr 2 CuO 6 (Bi2201), bilayer Bi 2 Sr 2 CaCu 2 O 8 (Bi2212) and trilayer Bi 2 Sr 2 Ca 2 Cu 3 O 10 (Bi2223) cuprate superconductors. Our study is based on both experimental data obtained by spectral ellipsometry on single crystals and theoretical calculations. The calculations are carried out within the framework of a classical shell model, which includes long-range Coulomb interactions and short-range interactions of the Buckingham form in a system of polarizable ions. Using the same set of the shell model parameters for Bi2201, Bi2212 and Bi2223, we calculate the frequencies of the Brillouin-zone center phonon modes of A 2u symmetry and suggest the phonon mode eigenvector patterns. We achieve good agreement between the calculated A 2u eigenfrequencies and the experimental values of the c axis TO phonon frequencies which allows us to make a reliable phonon mode assignment for all three Bi-based cuprate superconductors. We also present the results of our shell model calculations for the Γ-point A 1g symmetry modes in Bi2201, Bi2212 and Bi2223 and suggest an assignment that is based on the published experimental Raman spectra. The superconductivity-induced phonon anomalies recently observed in the c axis infrared and resonant Raman scattering spectra in trilayer Bi2223 are consistently explained with the suggested assignment.

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“…The close similarity between the thin film and ceramic data [l41 for (2212) phase samples means that this assumption is probably also valid for the latter. If this is the case, then the 'topmost' Cu-0 plane is buried -4.5 8, into the surface [34]. As the photoelectron flux from the sample is attenuated by a Beer-Lambert-type law, then the observed photoemission will be unduly weighted by the contributions from the topmost few layers, in this case Bi-0 (and to some extent .…”

Section: Resultsmentioning

confidence: 99%

Nondestructive preparation of thin-film Bi₂(Sr,Ca)₃Cu₂O_8+xsurfaces for photoemission studies by in situ oxygen annealing

Geeson

Golden

et al. 1989

Supercond. Sci. Technol.

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Abstract. The non-destructive technique of in situ oxygen annealing is used to prepare clean surfaces of c-axis oriented Bi,(Sr,Ca),Cu,O,+, thin films. Core and valence level photoemission spectra are consistent with those previously obtained by the authors from ceramic samples. In particular, the density of states at the Fermi level is comparable to that observed from polycrystalline samples but is not consistent with one-electron band-structure calculations.

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Crystal substructure and physical properties of the superconducting phaseBi4(Sr,Ca

Cited by 706 publications

References 7 publications

Ab initiocalculation of impurity effects in copper oxide materials

Ab initiocalculation of impurity effects in copper oxide materials

c-axis lattice dynamics in Bi-based cuprate superconductors

Nondestructive preparation of thin-film Bi₂(Sr,Ca)₃Cu₂O_8+xsurfaces for photoemission studies by in situ oxygen annealing

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Crystal substructure and physical properties of the superconducting phaseBi4(Sr,Ca

Cited by 706 publications

References 7 publications

Ab initiocalculation of impurity effects in copper oxide materials

Ab initiocalculation of impurity effects in copper oxide materials

c-axis lattice dynamics in Bi-based cuprate superconductors

Nondestructive preparation of thin-film Bi2(Sr,Ca)3Cu2O8+xsurfaces for photoemission studies by in situ oxygen annealing

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Nondestructive preparation of thin-film Bi₂(Sr,Ca)₃Cu₂O_8+xsurfaces for photoemission studies by in situ oxygen annealing