Eur. Phys. J. B 63, 179-185 (2008)
https://doi.org/10.1140/epjb/e2008-00233-7

Bond stretching phonon anomalies due to incommensurate charge density wave instabilities in high-T_c 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

Abstract

Phonon anomalies observed in various high T_c 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.