Eur. Phys. J. B 73, 509-513 (2010)
https://doi.org/10.1140/epjb/e2010-00030-9

Isotope effect and bond-stretching phonon anomaly in high-Tc cuprates

¹ National Institute of Physics and Nuclear Engineering, 077125 Bucharest-Magurele, Romania
² Institute of Applied Physics, 2028 Chişinău, R. Moldova
³ Dipartimento di Fisica E.R. Caianiello and C.N.I.S.M., Università degli Studi di Salerno, Baronissi, 84081, Italy
⁴ Laboratorio SuperMat, CNR-INFM, Salerno, Italy
⁵ I.I.A.S.S., Via G. Pellegrino 19, Vietri sul Mare, 84019, Italy

Corresponding author: scojocaru@theory.nipne.ro

Received: 22 September 2009
Revised: 30 November 2009
Published online: 27 January 2010

Abstract

We analyse a model where the anomalies of the bond-stretching LO phonon mode are caused by the coupling to electron dynamic response in the form of a damped oscillator and explore the possibility to reconstruct the spectrum of the latter from the phonon measurements. Preliminary estimates point to its location in the mid infrared region and we show how the required additional information can be extracted from the oxygen isotope effect on the phonon spectrum. The model predicts a significant measurable deviation from the “standard value” of the isotope effect even if the phonon frequency is far below the electron excitation spectrum, provided the latter is strongly incoherent. In this regime, which corresponds to the “mid infrared scenario”, the phonon linewidth becomes a sensitive and informative probe of the isotope effect.