Metal-Insulator Transition of Single-Crystal V₂O₃ through van der Waals Interface Engineering

Strongly correlated electron materials harbor interesting materials physics, such as high-T_c superconductivity, colossal magnetoresistance, and metal-insulator transition. These physical properties can be greatly influenced by the dimensionality and geometry of the hosting materials and their interaction strengths with underlying substrates. In a classic strongly correlated oxide vanadium sesquioxide (V₂O₃), the coexistence of a metal-insulator and paramagnetic-antiferromagnetic transitions at ∼150 K makes this material an excellent platform for exploring basic physics and developing future devices. So far, most studies have been focused on epitaxial thin films in which the strongly coupled substrate has a pronounced effect on V₂O₃, leading to the observations of intriguing phenomena and physics. In this work, we unveil the kinetics of a metal-insulator transition of V₂O₃ single-crystal sheets at nano and micro scales. We show the presence of triangle-like alternating metal/insulator phase patterns during phase transition, which is drastically different from the epitaxial film. The observation of single-stage metal-insulator transition in V₂O₃/graphene compared to the multistage in V₂O₃/SiO₂ evidence the importance of sheet-substrate coupling. Harnessing the freestanding form of the V₂O₃ sheet, we show that the phase transition of V₂O₃ sheet can generate a large dynamic strain to monolayer MoS₂ and tune its optical property based on the MoS₂/V₂O₃ hybrid structure. The demonstration of the capability in tuning phase transition kinetics and phase patterns using designed hybrid structure of varied sheet-substrate coupling strengths suggests an effective knob in the design and operation of emerging Mott devices.