Polaron formation in ferroelectric PbTiO3: an ab initio theoretical study.

We investigate the formation and characteristics of electron and hole polarons in the ferroelectric material PbTiO3 using a first-principles-based supercell approach and electron-phonon coupling calculations. We find that holes form two-dimensional large polarons spread across oxygen sites, driven by relatively weak hole-phonon coupling. In contrast, electrons experience stronger coupling with phonons and localize as small polarons on Ti sites. Spin-orbit coupling (SOC) has a negligible effect on hole polaron formation but significantly promotes the delocalization of electron polarons. These results provide fundamental insight into polaron physics in ferroelectric perovskites and suggest potential implications for carrier transport and separation in ferroelectric-based materials and devices.