Nonvolatile Control of Metal-Insulator Transition in VO 2 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 (VO 2 ), a representative correlated material, an approach to control a metal-insulator transition (MIT) behavior is developed by employing a heteroepitaxial structure with a ferroelectric BiFeO 3 (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 VO 2 at room temperature. The ferroelectrically-tunable MIT can be realized through the Mott transistor (VO 2 /BFO/SrRuO 3 ) 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 (≈10 2 ), long retention time (≈10 4 s), and high endurance (≈10 3 cycles). Furthermore, the structural phase transition of VO 2 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.