Magnetic vortex structure of CVD synthesized room-temperature ferromagnetic <b> <i>α</i> </b> -Fe2O3 nanosheets

The emergence of magnetic order in two-dimensional materials has stimulated extensive efforts to identify air-stable, room-temperature ferromagnets for applications in spintronics, magnonics, and quantum information technologies. Yet, most candidates are hindered by low Curie temperature and limited environmental stability. Here, we report the synthesis of air-stable α-Fe2O3 nanosheets with single phase and precisely controlled thicknesses ranging from 10 nm to several hundred nanometers via chemical vapor deposition. Magnetic characterizations by magnetic force microscopy and magneto-optical Kerr effect measurements reveal robust room-temperature ferromagnetism, along with magnetic vortex structure. Furthermore, using scanning nitrogen-vacancy center microscopy, we quantitatively depict the spatial variation of the magnetic stray field across a magnetic domain wall at an unprecedented resolution. The precise sample synthesis, macroscopic magnetometry, and high-resolution quantum imaging in our work not only provide a comprehensive understanding of magnetism in hematite-based nanostructures but also pave the way for their integration into potential spintronics applications.