Reversible formation-dissociation of polaron in rutile driven by electric field

Abstract

Density functional theory with Hubbard U correction is employed to study the polaron in rutile under external electric fields. It is found that electric-field-induced displacements of the ions enhance the sampling of the polaron configurations, which is helpful to find the most stable structure among local minima. More importantly, we demonstrate that with increasing electric field, the polaron may vanish, i.e. the excess electron can dissociate from the bounded Ti3+, and this process is reversible with the opposite electric field. The present findings shed light on more complex mechanisms for the polaron-related conductivity in oxides and corresponding devices. Impact statement The first ab initio demonstration of the polaron dynamics under electric fields provides a complete picture of the polaron in rutile, deepening the understanding of the conductivity in the oxides.

Keywords

• Polaron
• electric field
• rutile
• density functional theory