Vanadium: From cluster to semi-infinite crystal

Antiferromagnetic coupling between nearest neighbor vanadium atoms is discussed in the case of free-standing cluster and slabs, steps at the surface of V and V islands on Ag(001). In the self-consistent tight-binding derivation of the unrestricted approximation of the Hubbard-Hamiltonian, we have investigated the onset of magnetism in terms of the exchange integral J. For each topological arrangement of the V clusters [free-standing or as overlayer on Ag(001)], various possible magnetic states are considered and transition from nonmagnetic to magnetic order is characterized. The (001) surface is shown to present magnetism for a value of J lower than those for the other crystallographic faces.

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