Electron-phonon interaction enhanced by antiferromagnetic and superconducting fluctuations in cuprate superconductors

An electron-phonon interaction arising from the modulation of the superexchange interaction by phonons is studied within the theoretical framework of Kondo lattices. It is relevant in strongly correlated electron liquids in cuprate oxide superconductors, which lie in the vicinity of the Mott-Hubbard metal-insulator transition. It is enhanced by antiferromagnetic and superconducting fluctuations, which are developed mainly because of the superexchange interaction. When the enhancement of the electron-phonon interaction is large enough, it can explain the softening of phonons and kinks in the quasiparticle dispersion in cuprate oxide superconductors. However, the superexchange interaction itself must be mainly responsible for the formation of Cooper pairs.