Manipulating the Hydrogen‐Associated Insulator‐Metal Transition Through Artificial Microstructure Engineering

Abstract Hydrogen‐associated filling‐controlled Mottronics within electron‐correlated system provides a groundbreaking paradigm to explore exotic physical functionality and phenomena. Dynamically controlling hydrogen‐related phase transitions through external fields offers a promising route for designing protonic devices in multidisciplinary fields but faces high‐speed bottlenecks owing to slow bulk diffusion of hydrogens. Here, a promising pathway is presented to kinetically expedite the electronic state evolution in VO 2 system by taking advantage of artificial microstructure design. Typically, inclined domain boundary configuration and c R ‐faceted preferential orientation, simultaneously realized in VO 2 /Al 2 O 3 (102) heterostructure, significantly lower the diffusion barrier through creating an unobstructed conduit for hydrogen diffusion. As a result, the achievable switching speed through hydrogenation outperforms that of counterpart grown on widely‐utilized c ‐plane Al 2 O 3 substrate by 2–3 times, with resistive switching concurrently improved by an order of magnitude. Of particular interest, an anomalous uphill hydrogen diffusion observed for VO 2 with a diffusion highway fundamentally deviates from basic Fick's law, unveiling a deterministic role of hydrogen spatial distribution in tailoring electronic state evolution. The present work not only provides a powerful tuning knob for manipulating ionic evolution, endowing with great potential in designing advanced protonic devices, but also deepens the understanding of hydrogen‐associated insulator‐metal transition in electron‐correlated systems.