Polaron transport and Verwey transition in magnetite

Abstract

The enigmatic puzzle of the Verwey transition in magnetite Fe$_3$O$_4$ has been unresolved for almost a century. We present an ab initio-based model of the polaron transport combining kinetic Monte Carlo and molecular dynamics calculations to directly describe the coupling of polarons with lattice vibrations. Contrary to the Ihle-Lorentz small-polaron model, we find no significant change in the band structure across the Verwey transition, however, trimeron hopping is observed. The proposed model provides dc-conductivity in agreement with experimental data across the Verwey transition.