Modulating the Verwey Transition of Epitaxial Magnetite Thin Films by Ionic Gating

Abstract

Understanding the Verwey transition in magnetite (Fe3O4), a strongly correlated magnetic oxide, is a one-century-old topic that recaptures great attention because of the recent spectroscopy studies revealing its orbital details. Here, the modulation of the Verwey transition by tuning the orbital configurations with ionic gating is reported. In epitaxial magnetite thin films, the insulating Verwey state can be tuned continuously to be metallic showing that the low-temperature trimeron states can be controllably metalized by both the gate-induced oxygen vacancies and proton doping. The ionic gating can also reverse the sign of the anomalous Hall coefficient, indicating that the metallization is associated with the presence of a new type of carrier with competing spin. The variable spin orientation associated with the sign reversal is originated from the structural distortions driven by the gate-induced oxygen vacancies.