https://doi.org/10.1140/epjb/e2008-00233-7
Bond stretching phonon anomalies due to incommensurate charge density wave instabilities in high-Tc cuprates
1
Dipartimento di Fisica “E. R. Caianiello” and C.N.I.S.M., Università degli Studi di Salerno, via S. Allende, 84081 Baronissi (Sa), Italy
2
Université Joseph Fourier, B.P. 166, LPMC, 38042 Grenoble, France
3
National Institute of Physics and Nuclear Engineering, Bucharest-Magurele, 077125, Romania
4
Institute of Applied Physics, Chişinău, MD-2028, Moldova
Corresponding author: a citro@sa.infn.it
Received:
12
December
2007
Revised:
18
April
2008
Published online:
20
June
2008
Phonon anomalies observed in various high Tc cuprates are analyzed theoretically within the Hubbard-Holstein model in the limit of strong local electron correlations and in presence of long-range Coulomb interaction. The phonon self-energy is evaluated by taking into account the charge collective modes that become critical upon doping approaching an instability towards an incommensurate charge density wave (ICDW) driven by electron correlations. The doping dependence of phonon softening features and the highly distinctive phonon self-energy dependence on the wave vector agree with experiments. We discuss relevance of dynamical corrections to the density correlation function to achieve a sizeable bond-stretching phonon softening with a kink-like profile away from the zone boundary.
PACS: 71.10.Fd – Lattice fermion models / 74.72.-h – Cuprate superconductors / 71.38.-k – Polarons and electron-phonon interactions / 71.27.+a – Strongly correlated electron systems; heavy fermions
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2008