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TT: Fachverband Tiefe Temperaturen

TT 26: Metal-Insulator Transition

TT 26.6: Talk

Thursday, March 29, 2007, 15:15–15:30, H19

Electron-Phonon Interaction and Antiferromagnetic Correlations — •Giorgio Sangiovanni¹, Olle Gunnarsson¹, Erik Koch², Claudio Castellani³, and Massimo Capone^3,4 — ¹Max-Planck Institut für Festkörperforschung, Stuttgart — ²Institut für Festkörperforschung, Jülich — ³University of Rome "La Sapienza", Rome, Italy — ⁴INFM-SMC and Istituto dei Sistemi Complessi, Consiglio Nazionale delle Ricerche, Rome, Italy

Recent experiments suggesting sizeable lattice effects in the cuprates raise the 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.