Manipulating the metal-insulator transitions in correlated vanadium dioxide through bandwidth and band-filling control

Abstract

The metal-insulator transition (MIT) in correlated oxide systems opens up a new paradigm to trigger the abruption in multiple physical functionalities, enabling the possibility in unlocking exotic quantum states beyond conventional phase diagram. Nevertheless, the critical challenge for practical device implementation lies in achieving the precise control over the MIT behavior of correlated system across a broad temperature range, ensuring the operational adaptability in diverse environments. Herein, correlated vanadium dioxide (VO2) serves as a model system to demonstrate effective modulations on the MIT functionality through bandwidth and band-filling control. Leveraging the lattice mismatching between RuO2 buffer layer and TiO2 substrate, the in-plane tensile strain states in VO2 films can be continuously adjusted by simply altering the thickness of buffer layer, leading to a tunable MIT property over a wide range exceeding 20 K. Beyond that, proton evolution is unveiled to drive the structural transformation of VO2, with a pronounced strain dependence, which is accompanied by hydrogenation-triggered collective carrier delocalization through hydrogen-related band filling in t2g band. The present work establishes an enticing platform for tailoring the MIT properties in correlated electron systems, paving the way for the rational design in exotic electronic phases and physical phenomena.