Engineering Vertically-Growing V₂O₃ Nanosheets and Unveiling Their Novel Properties

Two-dimensional (2D) transition metal oxides (TMOs) have attracted considerable interest owing to their exceptional electronic, magnetic, and catalytic properties. Among them, V₂O₃ is particularly intriguing due to its well-known metal-insulator transition and correlated electron behavior. However, the challenge in controllably synthesizing ultrathin, high-quality V₂O₃ single crystals, stemming from its unique crystal structure and complex phase stability, has hindered a fundamental understanding of its electronic and magnetic properties. In this work, we demonstrate a Ge-assisted chemical vapor deposition (CVD) strategy that enables vertical and free-standing growth of high-quality V₂O₃ nanosheets. This method not only facilitates out-of-plane growth but also simplifies post-processing steps. The as-synthesized nanosheets attain thicknesses as thin as 0.72 nm. Structural characterization via x-ray diffraction (XRD), transmission electron microscopy (TEM), and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) confirms their high crystallinity and phase purity. Electrical characterization reveals a thickness-dependent metallic behavior at room temperature and a pronounced metal-insulator transition upon cooling. Moreover, magnetization measurements (M-H) indicate emerging ferromagnetic properties around 140 K. This study provides a reliable platform based on thickness-controlled V₂O₃ nanosheets for exploring correlated electronic and magnetic phenomena in the 2D limit and for developing advanced devices.