Magnetic two-dimensional chromium trihalides: structure, properties and modulation

The unique optical and electrical properties of two-dimensional (2D) materials provide a platform for novel van der Waals (vdW) heterojunction devices but the investigation of 2D magnetism is still limited. Recently, the emergence of long-range magnetic order atomically thin crystals expands 2D family, providing possibilities for the study of low-dimensional spin behavior and novel spintronics devices. As a specific member of magnetic van der Waals family, chromium trihalides (CrX3, X = Cl, Br, I) stimulated intensive interests on account of the newfangled magnetic properties. In this review, we briefly introduce the crystal structures, magnetism of the bulk and synthetic methods of 2D CrX3. Subsequently, the physical properties in atomically thin limit and magnetism manipulated by external field are presented. Next, some novel physical phenomena in CrX3 heterojunctions are discussed. Finally, the challenges and future directions are proposed. We focus on the intriguing physical phenomena in 2D magnetic CrX3 by combining related theoretical calculations and experimental results, providing a perspective on these emerging materials.