Influence of electron-phonon interaction on superexchange

TL;DR

This paper explores how electron-phonon interactions influence superexchange in magnetic insulators, showing that such coupling generally enhances superexchange across different models and parameter regimes.

Contribution

It provides a comparative analysis of electron-phonon effects on superexchange using exact diagonalization and perturbative methods in two models.

Findings

Electron-phonon coupling enhances superexchange.

Enhancement occurs in both adiabatic and anti-adiabatic regimes.

Results are consistent across different coupling models.

Abstract

We investigate the influence of electron-phonon coupling on the superexchange 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 modulation of the overlap integral are studied using exact diagonalization 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.