Magnetism of epitaxial3d-transition-metal monolayers on graphite

We have investigated the magnetism of hexagonal $3d$-metal monolayers, epitaxially adsorbed on the graphite (0001) surface, by spin-polarized electronic-structure calculations using the tight-binding linear muffin-tin orbital method. The calculations have been carried out in ferromagnetic, antiferromagnetic, and ferrimagnetic configurations for both adsorbed and unsupported monolayers. We find that the V monolayers are nonmagnetic and that the Fe, Co, and Ni monolayers are ferromagnetic. For the Mn monolayers, antiferromagnetic and ferrimagnetic configurations are more stable than the ferromagnetic one. For the unsupported Cr monolayer, antiferromagnetic and ferrimagnetic configurations exist, but they are almost degenerate with the nonmagnetic solution. This is due to the frustration of the antiferromagnetic nearest-neighbor coupling on the hexagonal lattice. The magnetic moments of the adsorbed monolayers are substantially reduced from their unsupported monolayer values and vanish completely in the case of Cr.