Metal-Insulator Transition of Single-Crystal V 2 O 3 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 (V 2 O 3 ), 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 V 2 O 3 , leading to the observations of intriguing phenomena and physics. In this work, we unveil the kinetics of a metal-insulator transition of V 2 O 3 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 V 2 O 3 /graphene compared to the multistage in V 2 O 3 /SiO 2 evidence the importance of sheet-substrate coupling. Harnessing the freestanding form of the V 2 O 3 sheet, we show that the phase transition of V 2 O 3 sheet can generate a large dynamic strain to monolayer MoS 2 and tune its optical property based on the MoS 2 /V 2 O 3 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.