A Two-Stage Model of Verwey Transition in Fe3O4: First-Principles Studies

Abstract

Fe3O4 undergoes a first-order metal-insulator transition, i.e., the Verwey transition at about 120 K. Despite extensive investigations focus on the Verwey transition, the exact underlying mechanism, particularly the evolution of the electronic structure during the transition, remains under debated. In this study, the lattice distortion near the Verwey transition is divided into several intermediate steps. The corresponding electronic structures and magnetic properties at each step are investigated by first-principles calculations. The results reveal that the Verwey transition can be regarded as a two-step phase transition containing a dynamic and a static trimeron network mode. Under the dynamic regime, the charge ordering pattern changes with lattice distortion. With further distortion, the system enters the static mode. Additionally, the variations of ferroelectricity and magnetic anisotropy with lattice distortion are investigated. The detailed calculation results may give a glimpse to the underlying physics of Verwey transition and promote the understanding of the three-Fe-site trimeron unit.