Carrier-doping and strain driven tuning of magnetic properties in the p-orbital monolayer metal-free ferromagnet T-XN₂ (X = Sb, Bi)

Two-dimensional non-metallic ferromagnetic states have attracted widespread attention due to their complete spin polarization, long spin relaxation times, and abundant availability, highlighting their potential applications in next-generation spintronic devices. Based on first-principles calculations, we predict the two-dimensional non-metallic ferromagnet T-XN₂ (X = Sb, Bi), which has a structure similar to T-MoS₂. Calculations of thermodynamic, kinetic, and mechanical properties confirm that they possess good stability. Spin polarization results indicate that the ground state of monolayer T-XN2 is ferromagnetic, with its magnetism arising from the direct p-orbital interactions between N atoms, unlike conventional d/f orbital magnetic materials. Furthermore, the ferromagnetism retains good stability under strain engineering and carrier doping. These results suggest that the magnetic properties of monolayer T-XN₂ hold significant fundamental research implications and make it a potential candidate material for non-metallic ferromagnetic devices.