Morphology-Dependent Room-Temperature Ferromagnetism in Undoped ZnO Nanostructures

Since Dietl et al. predicted that Co-doped ZnO may show room-temperature ferromagnetism (RTFM) in 2000, researchers have focused on the investigation of ferromagnetic ZnO doped with various transition metals. However, after decades of exploration, it has been found that undoped ZnO nanostructures can also show RTFM, which in general is dependent on ZnO morphologies. Here, we will give an overall review on undoped ZnO nanomaterials with RTFM. The advanced strategies to achieve multidimensional (quasi-0D, 1D, 2D, and 3D) ferromagnetic ZnO nanostructures and the mechanisms behind RTFM are systematically presented. We have successfully prepared ferromagnetic nanostructures, including thin films, horizontal arrays and vertical arrays. The existing challenges, including open questions about quantum-bound ZnO nanostructures, are then discussed.

Automated summary

Research on ferromagnetic ZnO nanostructures has shown that undoped ZnO may exhibit room-temperature ferromagnetism, which is dependent on ZnO morphologies. Advanced strategies and mechanisms have been systematically discussed, with progress made in preparing ferromagnetic nanostructures, but challenges remain in understanding quantum-bound ZnO nanostructures.