Synergistic Polaron Formation in the Hubbard-Holstein Model at Small Doping ...

We study the effect of dynamical Holstein phonons on the physics of the Hubbard model at
small doping using the dynamical cluster approximation. Non-local antiferromagnetic correlations
are found to significantly enhance the electron-phonon coupling, resulting in polaron formation for
moderate coupling strengths. At finite doping, the electron-phonon coupling is found to strongly
enhance the non-local spin correlations, indicating a synergistic interplay between the electron-
phonon coupling and antiferromagnetic correlations. Although it enhances the pairing interaction,
the electron-phonon coupling is found to decrease the superconducting transition temperature, due
to the reduction in the quasiparticle fraction.