MAGNETIC-PROPERTIES OF 3D TRANSITION-METAL NANOSTRUCTURES - CR AND V CLUSTERS EMBEDDED IN BULK FE

The magnetic and electronic properties of Cr-N and V-N clusters embedd ed in Fe are determined by using a realistic spd-band Hubbard-like mod el Hamiltonian. The spin-density distribution is calculated self-consi stently in the unrestricted Hartree-Fock approximation. The local magn etic moments mu(i) and the densities of electronic states rho(i)(epsil on) are obtained at different atoms i of the cluster and of the surrou nding Fe matrix. For all the studied clusters (N less than or equal to 51 atoms) the interface magnetic coupling between cluster and matrix moments is antiparallel. The mu(i) of Cr or V atoms at the interface a re enhanced by the presence of Fe atoms in their first-nearest-neighbo r shell. In most cases the Fe moments close to the cluster are slightl y reduced. In CrN the interface mu(i) are often much larger than the C r bulk moments [e.g., mu(i) = -1.30 mu(B) for Cr-4 in Fe]. In V-N larg e mu(i) are induced which decrease as N increases or as we move from t he interface to the interior of the cluster [e.g., mu(i) = -1.29 mu(B) for V-4 in Fe]. A remarkable interplay between the antiferromagnetism of Cr, the paramagnetism of V, and the ferromagnetism of Fe is obtain ed. The magnetic order within Cr-N (V-N) changes from ferromagnetic to antiferromagnetic for N greater than or equal to 9 (N greater than or equal to 6). This results in an interesting size dependence of the cl uster electronic density of states. [S0163-1829(98)02741-6].