Abstract

During the past decade a number of angle-resolved photoemission experiments (ARPES) have been performed in order to probe the low-energy quasiparticle dynamics of cuprate superconductors. Of direct relevance to the theory of cuprate superconductivity is the spectral anomaly observed at the binding energies of 50-80 meV along the nodal quasiparticle dispersions of various families of cuprates, including in particular Sr-doped La2SrCuO4 (LSCO¹). This anomaly - referred to as the ARPES kink – has been interpreted as the renormalization of the quasiparticle velocity resulting from an electron-boson interaction. However, no consensus has been reached yet on the nature of the boson mode involved. If the kink proved to be of phononic origin, then the associated electron-phonon coupling would be large enough to play an important role in the mechanism of high-temperature superconductivity. In this talk I will discuss a recent first-principles investigation of the role of the electron-phonon interaction in the photoemission spectra of LSCO . Our calculations indicate that the phonon-induced renormalization of the electron energies is almost one order of magnitude smaller than the effect observed in ARPES experiments, thereby ruling out the electron-phonon interaction as the exclusive origin of the observed kink². The general implications of the present findings for the interpretation of ARPES spectra will be discussed.

¹ A. Lanzara et al., Nature 412, 510 (2001).

² F. Giustino, M. L. Cohen, S. G. Louie, Nature 452, 975 (2008).