Nonvolatile Control of Metal–Insulator Transition in VO₂ by Ferroelectric Gating

Controlling phase transitions in correlated materials yields emergent functional properties, providing new aspects to future electronics and a fundamental understanding of condensed matter systems. With vanadium dioxide (VO₂ ), a representative correlated material, an approach to control a metal-insulator transition (MIT) behavior is developed by employing a heteroepitaxial structure with a ferroelectric BiFeO₃ (BFO) layer to modulate the interaction of correlated electrons. Owing to the defect-alleviated interfaces, the enhanced coupling between the correlated electrons and ferroelectric polarization is successfully demonstrated by showing a nonvolatile control of MIT of VO₂ at room temperature. The ferroelectrically-tunable MIT can be realized through the Mott transistor (VO₂ /BFO/SrRuO₃ ) with a remanent polarization of 80 µC cm^-2 , leading to a nonvolatile MIT behavior through the reversible electrical conductance with a large on/off ratio (≈10² ), long retention time (≈10⁴ s), and high endurance (≈10³ cycles). Furthermore, the structural phase transition of VO₂ is corroborated by ferroelectric polarization through in situ Raman mapping analysis. This study provides novel design principles for heteroepitaxial correlated materials and innovative insight to modulate multifunctional properties.