Magnetic Anisotropy in 2D van der Waals Magnetic Materials and their Heterostructures: Importance, Mechanisms, and Opportunities

Abstract 2D magnetism in atomically thin van der Waals (vdW) monolayers and heterostructures has attracted significant attention due to its promising potential for next‐generation spintronic and quantum technologies. A key factor in stabilizing long‐range magnetic order in these systems is magnetic anisotropy, which plays a crucial role in overcoming the limitations imposed by the Mermin‐Wagner theorem. This review provides a comprehensive theoretical and experimental overview of the importance of magnetic anisotropy in enabling intrinsic 2D magnetism and shaping the electronic, magnetic, and topological properties of 2D vdW materials. It begins by summarizing the fundamental mechanisms that determine magnetic anisotropy, emphasizing the contributions from strong ligand spin–orbit coupling of ligand atoms and unquenched orbital magnetic moments. A range of material engineering approaches is then examined, including alloying, doping, electrostatic gating, strain, and pressure, that have been employed to effectively tune magnetic anisotropy in these materials. Finally, open challenges and promising future directions in this rapidly advancing field are discussed. By presenting a broad perspective on the role of magnetic anisotropy in 2D magnetism, this review aims to stimulate ongoing efforts and new ideas toward the realization of robust, room‐temperature applications based on 2D vdW magnetic materials and their heterostructures.