Cmt off-diagonal electron-phonon coupling in high-Tc cuprates
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COJOCARU, Sergiu. Cmt off-diagonal electron-phonon coupling in high-Tc cuprates. In: Materials Science and Condensed Matter Physics, 13-17 septembrie 2010, Chișinău. Chișinău, Republica Moldova: Institutul de Fizică Aplicată, 2010, Editia 5, p. 331.
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Materials Science and Condensed Matter Physics
Editia 5, 2010
Conferința "Materials Science and Condensed Matter Physics"
Chișinău, Moldova, 13-17 septembrie 2010

Cmt off-diagonal electron-phonon coupling in high-Tc cuprates


Pag. 331-331

Cojocaru Sergiu12
 
1 Institute of Atomic Physics,
2 Institute of Applied Physics
 
Disponibil în IBN: 23 aprilie 2021


Rezumat

There exist convincing evidence that even for the overdoped samples the electron-phonon coupling (EPC) in high-Tc cuprates is sufficiently strong to be held responsible for a number of phonon anomalies, although its role for superconductivity remains unclear. However, this issue has mainly been studied within different models with Holstein kind of coupling (local and diagonal in electron number) which is hardly compatible with d-wave pairing symmetry. Several years ago it has been suggested (Allen, Ishihara, Nagaosa) that a relevant coupling in this context is generated by modulation of the electron hopping integral by lattice vibrations, the off-diagonal EPC. Based on this idea we consider a few open issues related to phonon spectra and electron spectra, in particular the strongly inhomogeneous and anisotropic softening of some phonon modes and anomalies of the electron spectra in the related energy region (60-80 meV). We analyse several universal features of these spectra and demonstrate that the earlier introduced off-diagonal coupling can not explain the details observed in recent experiments. Next we introduce a new coupling in the same class, which can account for the universality of the main features of the anomalies and reproduces their quantitative characteristics, for instance an abrupt softening with 15-20 % of the bond-stretching mode at momemntum of 0.25 rlu for both hole and electron doped materials.