First-Principles Prediction of Metal-Free Magnetism and Intrinsic Half-Metallicity in Graphitic Carbon Nitride

Transition metal-free magnetism and half-metallicity recently has been the subject of intense research activity due to its potential in spintronics application. Here we, for the first time, demonstrate via density functional theory that the most recently experimentally realized graphitic carbon nitride ($g\mathrm{\text{−}}{\mathrm{C}}_4{\mathrm{N}}_3$) displays a ferromagnetic ground state. Furthermore, this novel material is predicted to possess an intrinsic half-metallicity never reported to date. Our results highlight a new promising material toward realistic metal-free spintronics application.

Figure 1

(a) A top and (b) side view of the fully optimized ($1\times 1$) $g\mathrm{\text{−}}{\mathrm{C}}_4{\mathrm{N}}_3$; (c) a top view and (d) a side view of a ($2\times 2$) reconstructed $g\mathrm{\text{−}}{\mathrm{C}}_4{\mathrm{N}}_3$. Green and blue balls represent C and N atoms, respectively.

Figure 2

Magnetic moment and relative energies for (a) FM, (b) AFM, and (c) NM states in a ($2\times 2$) reconstructed $g\mathrm{\text{−}}{\mathrm{C}}_4{\mathrm{N}}_3$.

Figure 3

Band structure and spin-resolved total density of state for a ($1\times 1$) unreconstructed [(a) and (c)] and a ($2\times 2$) reconstructed [(b) and (d)] $g\mathrm{\text{−}}{\mathrm{C}}_4{\mathrm{N}}_3$, respectively. The short dotted line indicates the Fermi level.

Figure 4

Projected DOS on the $p$ orbital of N and C atoms (a) and (b) and 3D isosurface plots of magnetic charge density (${\rho }_{\uparrow }-{\rho }_{\downarrow }$) for a ($1\times 1$) unreconstructed (a) and a ($2\times 2$) reconstructed (b) $g\mathrm{\text{−}}{\mathrm{C}}_4{\mathrm{N}}_3$ in the FM ground state. The short dotted line indicates the Fermi level.

Figure 5

The fluctuations of temperature (a) and ferromagnetic moment (b) as a function of the molecular dynamic simulation step at 300 K. (c) and (d) are similar to (a) and (b), respectively, but for another molecular dynamic run at 500 K.

Figure 6

(a) Band structures and (b) DOS calculated by the HSE06 functional for a ($1\times 1$) $g\mathrm{\text{−}}{\mathrm{C}}_4{\mathrm{N}}_3$. The short dotted line indicates the Fermi level.