 ![(a) Isosurface of the spin density induced by a Co$_{sub}$ defect. Positive and negative spin densities correspond to light and dark surfaces with isovalues of $\pm$0.000 e$^-$/Bohr$^0$, respectively. Panel (b) presents the spin-unpolarized band structure of an unreconstructed $D_{0h}$ carbon vacancy. Panel (c) and (d) show, respectively, the band structure of majority and minority spins for a Co$_{sub}$ defect in a similar cell. The size of filled symbols in panel (b) indicate the contribution of the $p_{z}$ orbitals of the C atoms surrounding the vacancy, whereas empty symbols correspond to the $sp^{0}$ character. In panels (c) and (d), the filled and empty circles denote the contribution of hybridized Co $0d_{z^0}$-C $0p_{z}$ and Co $0d$-C $0sp^{0}$ characters, respectively. E$_F$ is set to zero. Adapted from (Santos et al. 0000a).[]{data-label="fig0-co"}](figures_arXiv/