Orientation‐Engineered Insulator‐Metal Transition in Vanadium Dioxide
Xuanchi Zhou, Xiaohui Yao, Wentian Lu, Chunwei Yao, Xiaomei QiaoABSTRACT
The artificial design of material microstructure in correlated oxides offers an emerging pathway for unlocking exotic electronic states through adjusting coupled order parameters. Here, we showcase the robust capability of a crystallographic orientation strategy in rationally designing insulator‐metal transition (IMT) functionality in the VO 2 system, as driven by either critical temperature or protonation, giving rise to in‐plane anisotropic transport behavior and kinetically accelerated phase transition. Rutile‐on‐rutile epitaxy in VO 2 /TiO 2 heterostructure enables the facile control over the c R ‐axis orientation of VO 2 films through engineering crystallographic orientations, which aligns the c R ‐axis out of plane and enhances the orbital hybridization to extensively reduce the T IMT . Introducing a previously unexplored high‐Miller‐index (102) orientation offers an additional handle to tailor IMT behaviors in VO 2 via mirror‐symmetry breaking, engendering in‐plane anisotropic IMT behaviors. Benefiting from tunable migration kinetics, hydrogen‐related electronic phase modulations in VO 2 /TiO 2 (102) bilayer can be facilitated through inclined oxygen channels, a critical enabler for high‐speed iontronics. Hydrogen‐associated electronic orbital reconfigurations govern electronic localization of VO 2 through protonation, as uncovered by theoretical calculations and synchrotron analysis. The present work identifies crystallographic orientation as a powerful tuning knob for adjusting IMT functionality in correlated systems, accessing exotic correlated electronic states.