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.
Keywords: Mott-tronics; correlated electrons; epitaxial heterostructures; ferroelectric polarization; metal-insulator transition; vanadium dioxide.
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