Electric Field Control of Metal–Insulator Transition in Charge-Ordered Fe₂BO₄

The structure and electric properties of single-crystal Fe₂BO₄ are measured by in situ high-resolution X-ray diffraction combined with current–voltage (I–V) measurements. A superstructure due to charge ordering (CO) is found at room temperature, and the superstructure peak disappears when the applied electric field exceeds a certain threshold. I–V characteristics show a sharp resistance drop, indicating a metal–insulator transition (MIT) induced by applied voltage and revealing electron–lattice coupling, which is due to the Joule heating effect. Moreover, the Fe₂BO₄ single crystal exhibits a multidomain monoclinic phase in its original state, which transforms into a single-domain orthorhombic phase when a voltage of 200 V is applied. MIT, CO state collapse, and structural phase change have been observed simultaneously and indicate that the CO structural phase change can be controlled by an electric field.