Inversion of K3C60 reflectance data

Marsiglio, F.; Startseva, T.; Ćarbotte, J. P.

doi:10.1016/s0375-9601(98)00373-9

Cited by 87 publications

(130 citation statements)

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“…It is known that the electron-phonon spectral density α 2 F (ω) can be obtained through inversion of optical data. Marsiglio et al 60 introduced a dimensionless function W (ω) which is defined as the second derivative of the normal state optical scattering rate…”

Section: Strong Electron-phonon Coupling Features Along the Antinomentioning

confidence: 99%

Pairing interactions and pairing mechanism in high-temperature copper oxide superconductors

Zhao

2005

Phys. Rev. B

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The polaron binding energy Ep in undoped parent cuprates has been determined to be about 1.0 eV from the unconventional oxygen-isotope effect on the antiferromagnetic ordering temperature. The deduced value of Ep is in quantitative agreement with that estimated from independent optical data and that estimated theoretically from the measured dielectric constants. The substantial oxygenisotope effect on the in-plane supercarrier mass observed in optimally doped cuprates suggests that polarons are bound into the Cooper pairs. We also identify the phonon modes that are strongly coupled to conduction electrons from the angle-resolved photoemission spectroscopy, tunneling spectra, and optical data. We consistently show that there is a very strong electron-phonon coupling feature at a phonon energy of about 20 meV along the antinodal direction and that this coupling becomes weaker towards the diagonal direction. We further show that high-temperature superconductivity in cuprates is caused by strong electron-phonon coupling, polaronic effect, and significant coupling with 2 eV Cu-O charge transfer fluctuation.

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Section: Strong Electron-phonon Coupling Features Along the Antinomentioning

confidence: 99%

Pairing interactions and pairing mechanism in high-temperature copper oxide superconductors

Zhao

2005

Phys. Rev. B

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“…20,21 Unfortunately, the extraction of the spectral functions from these experiments, for a variety of reasons, is technically much more challenging than from tunneling data. Therefore, the main experimental tool for the determination of the EPI in superconductors so far is the tunneling measurement.…”

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Extraction of the electron-phonon interaction from tunneling data in the multigap superconductorMgB2

et al. 2003

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The direct inversion of the Eliashberg equations ͑EE͒ in case of a multiband superconductor is a mathematically ill-defined problem, because it is not possible to obtain several band splitted electron-phonon spectral functions ␣ 2 F i j () from a single function of the tunnel current. In the present work we follow another direction and calculate the tunneling density of states ͑DOS͒ of MgB 2 for different tunneling directions by directly solving the two-band EE in the real-axis formulation. This procedure reveals the fine structures of the DOS due to the optical phonons. Then we show that the numeric inversion of the standard single-band EE, when applied to the two-band DOS of MgB 2 , underestimates the strength of certain phonon branches ͑e.g., the E 2g ) in the extracted ␣ 2 F(). The fine structures produced by the two-band interaction at energies between 20 and 100 meV turn out to be clearly observable only for tunneling along the ab planes and at very low temperature. Only in this case it is possible to extract some information on the -band contribution to the spectral functions. For any other tunneling direction, the -band contribution is dominant and almost coincides with the whole ␣ 2 F() for tunneling along the c axis. Our results are compared with recent experimental tunneling and point-contact data. There is a growing consensus that the superconductivity in MgB 2 with a critical temperature T c Ӎ40 K ͑Ref. 1͒ is driven by the electron-phonon interaction ͑EPI͒ ͑for a recent review see Ref.2͒. An important subject to address for a proper understanding of the surprising physical properties of this material is the character of the order parameter ͑or superconducting gap͒: is it constant over the whole Fermi surface, or strongly momentum dependent? The idea of multiband superconductivity in MgB 2 ͑Refs. 3-9͒ is supported by many recent experimental results from tunneling, 10-12 point contact,13-15 and specific-heat capacity measurements. 6,16 These data directly support the picture that the superconducting gap has two different values on two qualitatively different parts of the Fermi surface, one ⌬ for the two quasi-twodimensional bands and another one ⌬ for the pair of three-dimensional ͑3D͒ bands. 3,5While, within first-principles calculations of the electronic structure and the EPI in this compound, there is an agreement 17 on this qualitative picture, still disagreement is present about the precise values of characteristic frequencies and coupling constants. According to most calculations, 3,18,19,8 the EPI or, equivalently, the Eliashberg spectral function ␣ 2 F() ͑EF͒ is dominated by the optical boron bond-stretching E 2g phonon branch of around 60-70 meV.In principle, photoemission lineshapes or the deviation of the far-IR absorption from the Drude law are controlled by the same Eliashberg functions as tunneling or their transport counterparts, so that optical measurements can also deliver information on the EPI. 20,21 Unfortunately, the extraction of the spectral functions from these experiments, fo...

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“…The initial calculations conducted with the use of the Eliashberg equations indicate that in the case of K 3 C 60 the electron-phonon interaction can independently induce the superconducting phase [16]. According to that, the precise calculation of the basic thermodynamic parameters seems to be an essential matter.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic Properties of the Superconducting State in the K₃C₆₀Fulleride

Szczȩśniak

Barasiński

2009

Acta Phys. Pol. A

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Inversion of K3C60 reflectance data

Cited by 87 publications

References 20 publications

Pairing interactions and pairing mechanism in high-temperature copper oxide superconductors

Pairing interactions and pairing mechanism in high-temperature copper oxide superconductors

Extraction of the electron-phonon interaction from tunneling data in the multigap superconductorMgB2

Thermodynamic Properties of the Superconducting State in the K₃C₆₀Fulleride

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Inversion of K3C60 reflectance data

Cited by 87 publications

References 20 publications

Pairing interactions and pairing mechanism in high-temperature copper oxide superconductors

Pairing interactions and pairing mechanism in high-temperature copper oxide superconductors

Extraction of the electron-phonon interaction from tunneling data in the multigap superconductorMgB2

Thermodynamic Properties of the Superconducting State in the K3C60Fulleride

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Product

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Thermodynamic Properties of the Superconducting State in the K₃C₆₀Fulleride