Prediction of half-metallic ferromagnetism in C-doped CdS nanowire

The geometric, energetic, and magnetic properties of nonmagnetic carbon (C)-doped cadmium sulfur (CdS) nanowires (NWs) are investigated based on first-principles calculations. We find that the two C dopants are most stable when they are close to each other in the surface sites, exhibiting half-metallic (HM) behavior with a net magnetic moment of 2.0 μ_B C⁻¹. The magnetic interaction between the nearest and next-nearest C dopants results in a strong ferromagnetic (FM) coupling. However, the ground state of the system tends to be paramagnetic when the distance between the C dopants is larger than 6.2 Å. The HMFM order in C-doped CdS NWs, which is sensitive to the confinement of electrons in the radial direction and the curvature of the NW's surface, can be attributed to hole-mediated double exchange through the strong p–p interaction between carbon dopants. These predicted results endow CdS NWs potential applications in spintronics.