Electron-Phonon Interaction and Antiferromagnetic Correlations

Recent experiments suggesting sizeable lattice effects in the cuprates raisethe issue of the the role of electron-phonon (e-ph) interaction in strongly correlated systems. By means of Dynamical Mean-Field Theory, we show that, in the Hubbard-Holstein model, antiferromagnetic (AF) correlations strongly enhance the effects of the e-ph coupling with respect to the paramagnetic phase,even though the net effect of the Coulomb interaction is a moderate suppression of the e-ph interaction. Doping weakens the AF correlations and reduces the effects of the e-ph, leading to a scenario in which the tendency to polaron formation is weakened by doping, in agreement with the experimental results [1]. \newline \newline [1] G. Sangiovanni {\it et al.}, Phys. Rev. Lett. {\bf 97}, 046404 (2006)