Magnetic properties of C-N planar structures: d(0) ferromagnetism and half-metallicity

We investigate, from first principles calculations, the magnetic properties of planar carbon nitride structures with the lowest formation energies within twenty eight distinct stoichiometries and porosities. Surprisingly, we find that 3/4 of the low-energy carbon nitride structures present energetically favorable magnetic phases, and that more than 3/10 are ferromagnetic. This suggests that d(0) magnetism is a usual feature in this class of materials. Notably, within the energetically favorable ferromagnetic structures, we find that two structures have very high stabilization energies for ferromagnetic order, one having the highest predicted so far for this class of materials. We also find that several structures are half-metals, and one structure is half-zero-gap semiconductor (semicondutor in one spin channel, and graphene-like in the other channel).