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Falter, Claus; Klenner, M.; Hoffmann, Georg

doi:10.1103/physrevb.52.3702

Cited by 39 publications

(56 citation statements)

References 20 publications

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“…Consequently, this issue has been addressed in several theoretical papers. Falter and co-workers start from the electronic band structure calculated within the local density approximation (LDA) [10,11,12,13,14]. The failure of LDA theory to reproduce the insulating ground-state of the undoped parent compounds is remedied by suitably imposing the long-wavelength limit of the electronic polarizability [14].…”

Section: Discussionmentioning

confidence: 99%

Oxygen phonon branches in overdopedLa1.7Sr0.3Cu3O4

2006

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The dispersion of the Cu-O bond-stretching vibrations in overdoped La1.7Sr0.3CuO4 (not superconducting) has been studied by high resolution inelastic neutron scattering. It was found that the doping-induced renormalization of the so-called breathing and the half-breathing modes is larger than in optimally doped La1.85Sr0.15CuO4. On the other hand, the phonon linewidths are generally smaller in the overdoped sample. Features observed in optimally doped La1.85Sr0.15CuO4 which suggest a tendency towards charge stripe formation are absent in overdoped La1.7Sr0.3CuO4.

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Section: Discussionmentioning

confidence: 99%

Oxygen phonon branches in overdopedLa1.7Sr0.3Cu3O4

2006

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“…As discussed in [ [4,14] by calculating the orbital occupation numbers Q m of the m (tight-binding) orbital in question,…”

Section: Review Of the Theory And Sketch Of The Modelmentioning

confidence: 99%

“…For the calculation of P we have used so far an 11-band tight-binding model (11 BM) for the electronic bandstructure of the CuO plane including all the Cu 3d and O xy 2p orbitals. In order to account for the interaction between different layers we have extended this two-dimensional model introducing interlayer couplings in a parametrized form from the outside [3,4].…”

Section: Introductionmentioning

confidence: 99%

“…The investigations in the extended 11 BM for modes propagating along the c-axis lead to the possibility of a low-lying plasmon, mixing strongly with the phonons of appropriate symmetry and moreover, predict an increase of the already large coupling strength found in the adiabatic approximation if dynamical screening is considered in the nonadiabatic case. In particular, such a scenario appears if the interlayer hopping parameters in the three-dimensional extended 11 BM are chosen to give a maximal bandwidth in c-direction of about 50 meV at the Fermi level [3,4] representing the anisotropy found in typical first principles calculations of the electronic bandstructure based on the LDA, see e.g. [8 to 10].…”

Section: Introductionmentioning

confidence: 99%

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Screening and Phonon-Plasmon Scenario as Calculated from a Realistic Electronic Bandstructure Based on LDA for La2CuO4

Falter

Klenner

Hoffmann

1998

phys. stat. sol. (b)

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The investigations performed in this work primarily deal with the question whether or no phonon±plasmon coupling along the c-axis in metallic La 2 CuO 4 will occur in case a realistic electronic bandstructure based on the local density approximation (LDA) is employed for the calculation of the electronic polarizability P and the dielectric matrix e. Phonon±plasmon mixing will appear in a significant way if the frequency of the free, uncoupled plasmon, as determined from the zeros of the dielectric matrix e, will fall into the frequency range of the phonon modes of appropriate symmetry coupling to the plasmon. For such a possibility to arise the dispersion of the electronic bandstructure along the c-axis must be sufficiently weak (small bandwidth). Qualitatively, we recently have studied phonon±plasmon mixing by using an 11-band tight binding model for the electronic bandstructure of the CuO plane, while the electronic bandstructure along the c-axis was introduced from the outside applying suitable interlayer couplings in parametrized form. In the present calculation the electronic bandstructure employed for the calculation of P and e, respectively, results from a complete tight-binding representation of the first-principles LAPW data including La 5d, Cu 3d, 4s, 4p and O 2p states (31-band model). No additional assumptions concerning the interlayer coupling are introduced in contrast to the 11-band model. Besides the nonadiabatic regime along the L $ 0Y 0Y 1 direction where dynamical screening and phonon±plasmon mixing comes into play, the phonon dispersion is also calculated for the main symmetry directions using the adiabatic approximation, i.e. assuming static screening. Besides other features, from this calculation the growing importance of the itinerant component of the charge response in the CuO plane to achieve high-T c values can be extracted. The charge fluctuations and the self-consistent changes of the crystal potential at the ion sites as induced by the symmetrical apical oxygen breathing mode at the Z point (O z Z ), being important for nonlocal electron±phonon interaction and pair binding, are calculated for the phonon-like and plasmon-like modes. Furthermore, a comparison is made with recent inelastic neutron scattering results for certain phonon anomalies. Finally, a possible solution concerning the apparent inconsistency of the current interpretation of the neutron c-axis data with the infrared c-axis optical spectra in La 2 CuO 4 is shortly outlined. Based on this discussion, the possibility for the application of a typical (LDA) bandstructure result for the description of the c-axis response in LaCuO the other HTSCs is estimated.

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“…The local, rigid part of the electronic charge response and the EPI is approximated by an ab initio RIM taking into account ion-softening in terms of (static) effective ionic charges and scaling of the short-ranged part of certain pair potentials between the ions to simulate covalence effects in the model. This is done in such a way that the energy-minimized structure is as close as possible to the experimental one 18 . Structure optimization and energy minimization is very important for a reliable calculation of the phonon dynamics through the dynamical matrix.…”

Section: Sketch Of the Theory And Modelingmentioning

confidence: 99%

Microscopic modeling of phonon dynamics and charge response in metallicBaBiO3

2007

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We use our recently proposed microscopic modeling in the framework of linear response theory to investigate the complete phonon dispersion, the phonon density of states, certain phonon-induced electronic charge distributions and charge fluctuations (CF's) for anomalous soft modes of metallic BaBiO3 in its simple cubic phase where superconductivity with Tc up to 32 K appears. The theoretical approach already has been applied successfully to the cuprate high-temperature superconductors (HTSC's), simple ionic crystals (NaCl, MgO) and perovskite oxides (SrTiO3, BaTiO3). It is well suited for materials with a strong component of ionic binding and especially for "ionic" metals. In particular, the giant phonon anomalies related to the breathing vibration of the oxygen as found experimentally in superconducting doped Ba0.6K0.4BiO3, resembling those observed in the high Tc cuprates, are investigated. The origin of these anomalies is explored and attributed to a strong nonlocal coupling of the displaced oxygen ions to CF's of ionic type, essentially of the Bi6s-and Bi6p orbital. This points to the importance of both of these states at the Fermi energy. Starting from an ab-initio rigid ion model (RIM) we calculate the effect on the lattice dynamics and charge response of the most important electronic polarization processes in the material, i. e. CF's and dipole fluctuations (DF's). Taking into account these electronic degrees of freedom in linear response theory, we obtain a good agreement with the measured phonon dispersion and in particular with the strong phonon anomalies.

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Phonon renormalization andc-axis phonon-plasmon mixing inLa2CuO4

Cited by 39 publications

References 20 publications

Oxygen phonon branches in overdopedLa1.7Sr0.3Cu3O4

Oxygen phonon branches in overdopedLa1.7Sr0.3Cu3O4

Screening and Phonon-Plasmon Scenario as Calculated from a Realistic Electronic Bandstructure Based on LDA for La2CuO4

Microscopic modeling of phonon dynamics and charge response in metallicBaBiO3

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