First-principles study of electron-phonon interactions in SrTiO3

The discovery of a two-dimensional electron liquid on the surface of doped SrTiO3 (STO) and the confirmation of high-temperature superconductivity at the FeSe/SrTiO3 interface have attracted considerable interest in the electron-phonon physics of STO. In this work we focus on the polaron satellites observed in the angle-resolved photoelectron spectra of STO, and investigate their origin using the many-body electron-phonon self-energy in the Migdal approximation, augmented with the cumulant expansion formalism. By comparing our first-principles calculations with experiments we investigate the microscopic mechanisms that give rise to the observed polaron satellites.