2D magnets are of interest for applications such as spintronics, enabling the design of more compact and energy-efficient devices. 2D magnets based on iron oxide (Fe2O3), in particular, are stable in air, which simplifies their processing for eventual applications. Among the various polymorphs of this material, γ-Fe2O3 stands out as highly promising due to its high magnetic order temperature of 950 K (that is, the point at which the material retains its magnetic properties). However, γ-Fe2O3 is thermodynamically unstable when the particle size exceeds 50 nm, which limits its applications. Wuhong Xue, Huali Yang, Xiaohong Xu and colleagues demonstrate the controllable growth of 2D γ-Fe2O3 using space-confined chemical vapor deposition (CVD) on a mica substrate. The mica substrate is particularly beneficial because of its smooth surface and lack of dangling bonds, making it easier for reactive atoms to move and come together to form crystals. With this approach, the lateral size of the obtained nanoflakes could be adjusted to reach tens of micrometres. Furthermore, the arrangement of magnetic domains within a γ-Fe2O3 nanoflake was found to be affected by the nanoflake’s lateral dimensions.