Synthesis of Stable 2D Ferrimagnetic Fe₃O₄ Nanosheets and Their Anomalous Magnetic Transport Properties Below the Verwey Transition

2D magnetic materials offer a versatile platform for exploring emergent phenomena in condensed matter physics and spintronics. However, their limited environmental stability and relatively low magnetic ordering temperatures hinder both fundamental research and potential applications. Here, the synthesis of ultrastable 2D Fe₃O₄ nanosheets with a high Curie temperature (T_C) via a chemical vapor deposition (CVD) method employing an intermediate-state reduction strategy is reported. Comprehensive electrical and magnetic transport measurements reveal a pronounced metal-semiconductor-insulator transition (Verwey transition), accompanied by anomalous anisotropic magnetoresistance (AMR) exhibiting periodic evolution behaviors below Verwey transition temperature (T_V). Temperature-dependent Raman spectroscopy combined with first-principles calculations demonstrates that the Verwey transition originates from charge ordering and the formation of trimerons. The anomalous AMR is attributed to the competition between intrinsic uniaxial anisotropy and trimeron-mediated magnetic anisotropy. These findings advance the fundamental understanding of the Verwey transition, provide guidance for the scalable fabrication of 2D Fe₃O₄ nanosheets, and may facilitate future applications in spintronics.