Selective local modification of electronic transitions in Mott materials by Laser-induced oxygen doping*

Vanadium oxides are strongly correlated materials which exhibit a variety of collective properties including metal-insulator transitions. The structural and magnetic properties are significantly influenced by variations in oxygen stoichiometry. Nevertheless, thin films of stoichiometric vanadium oxides generally exhibit a single Metal-Insulating Transition (MIT), and frequently require high thermal treatment and prolonged processing times to achieve desirable electrical characteristics. This limitation restricts their compatibility and functionality for different applications in science and technology. We developed a novel technique involving laser-induced oxygen doping. This technique allows selective control of VO₂, V₃O₅ and V₄O₇ in a 100 nm-thick V₂O₃ thin film matrix. We successfully induced multiple phases within a micron-sized area while maintaining their distinct and separate electronic transitions. Various laser scanning methods were developed useful to enhance the MIT transition of VO₂ by approximately 20 K. Additionally, both the resistance ratio and magnitude of the thermal hysteresis are controllable using these strategies. These effects are connected to in-plane strain originating from the adjacent V₂O₃ layer, a conclusion supported by thermomechanical simulations. Our approach offers an alternative pathway for strategically modifying the local electronic properties of Mott materials, opening up a wide range of potential applications.