INFLUENCE OF ELECTRON-PHONON INTERACTION ON SUPEREXCHANGE

We investigate the influence of electron-phonon coupling on the supere xchange interaction of magnetic insulators. Both the Holstein-Hubbard model where the phonons couple to the electron density, as well as an extended Su, Schrieffer, Heeger model where the coupling arises from m odulation of the overlap integral are studied using exact diagonalizat ion and perturbative methods. In all cases for both the adiabatic (but non-zero frequency) and anti-adiabatic parameter regions the electron -phonon coupling is found to enhance the superexchange.