Prediction of carbon-based metal-free compounds with antiferromagnetism and superhardness

• Published in: Journal of magnetism and magnetic materials 2024-08, Vol.603, p.172250, Article 172250
• Main Authors: Wu, Haiping, Zhang, Huanle, Kan, Erjun, Qian, Yan
• Format: Article
• Language: English
• Subjects: Antiferromagnetism; Carbon-based compounds; Semiconductor; Superhard
• ISSN: 0304-8853
• DOI: 10.1016/j.jmmm.2024.172250

Magnetic superhard materials are still scarce, although they are very important to magnetic devices in extreme environment. Here, we predict a series of antiferromagnetic carbon-based compounds through stacking diamane and 2D C4N3. The result exhibits that all the ground states of these compounds display antiferromagnetic ordering and superhard nature. The antiferromagnetism originates from the unpaired electrons of the low-coordinated C atoms at the interface. Interestingly, their hardness, magnetic moment, dynamic and mechanical stabilities are independent of the stacking sequence of the two precursors. The Vickers hardness is ∼70 GPa given by Chen model, the magnetic moment is ∼0.44μB. Notably, the magnetic moment is insensitive to the external pressure, whereas the magnetic transition temperature would increase with increasing the external pressure. On the contrary, the electronic property is strongly dependent on the stacking sequence, resulting in energy gaps ranging from 1.00 to 1.30 eV, despite all behaving as semiconductors. This work opens a potential way to design magnetic carbon-based materials with superhard feature. •Metal-free carbon-based compounds are designed by stacking 2D nanosheets.•The low-coordinated atoms at the interface induce magnetism for all compounds.•All the compounds exhibit properties of superhard semiconductors.•The electronic structure depends on the stacking sequence.