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SUMMARY:Electron-phonon contribution to the photoemission kink in cuprate 
 superconductors - Dr Feliciano Giustino\, University of Oxford
DTSTART:20090115T141500Z
DTEND:20090115T151500Z
UID:TALK15647@talks.cam.ac.uk
CONTACT:Dr Jonathan Keeling
DESCRIPTION:During the past decade a number of angle-resolved photoemissio
 n \nexperiments (ARPES) have been performed in order to probe the \nlow-en
 ergy quasiparticle dynamics of cuprate superconductors. \nOf direct releva
 nce to the theory of cuprate superconductivity is \nthe spectral anomaly o
 bserved at the binding energies of 50-80 meV along \nthe nodal quasipartic
 le dispersions of various families of cuprates\, \nincluding in particular
  Sr-doped La2SrCuO4 (LSCO[1]). This anomaly \n- referred to as the ARPES k
 ink - has been interpreted as the \nrenormalization of the quasiparticle v
 elocity resulting from an \nelectron-boson interaction. However\, no conse
 nsus has been reached \nyet on the nature of the boson mode involved. If t
 he kink proved to be \nof phononic origin\, then the associated electron-p
 honon coupling would \nbe large enough to play an important role in the me
 chanism \nof high-temperature superconductivity. In this talk I will discu
 ss \na recent first-principles investigation of the role of the electron-p
 honon \ninteraction in the photoemission spectra of LSCO. Our calculations
  \nindicate that the phonon-induced renormalization of the electron \nener
 gies is almost one order of magnitude smaller than the effect \nobserved i
 n ARPES experiments\, thereby ruling out the electron-phonon \ninteraction
  as the exclusive origin of the observed kink[2].\nThe general implication
 s of the present findings for the interpretation \nof ARPES spectra will b
 e discussed.\n\nfn1. A. Lanzara et al.\, "Nature 412\, 510":http://dx.doi.
 org/10.1038/35087518 (2001).\n\nfn2. F. Giustino\, M. L. Cohen\, S. G. Lou
 ie\, "Nature 452\, 975":http://dx.doi.org/10.1038/nature06874 (2008). 
LOCATION:TCM Seminar Room\, Cavendish Laboratory
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