Ab initio study of polaron dynamics in transition metal oxides

In the highly insulating materials like transition metal oxides, electrons strongly couple with neighboring lattice sites, severely deforming the surrounding lattice and leading to localized states, and they are self-trapped by self-induced local lattice distortions. As a result, electronic transport is mostly dominated by the small polaron hopping from lattice site to lattice site rather than the drift motion. Here, using the first-principles density functional theory calculations, we explore the polaron dynamics in the insulating Fe₂O₃. We find that the polaron hopping occurs only in the two dimensional FeO plane and its hopping barrier is highly susceptible to the lattice deformation induced by intrinsic oxygen vacancy and extrinsic Sn dopant. We expect our results to provide important information for development of highly efficient Fe₂O₃-based electrochemical device.