MAGNETIC-PROPERTIES OF 4D TRANSITION-METAL CLUSTERS

We analyze the stability of magnetic states obtained within the tight- binding model solved by molecular dynamics for cube-octahedral (fee) a nd icosahedral clusters of 3d (Ni and Co) and 4d (Pd, Rh, and Ru) tran sition metals. The magnetic states are stabilized by the Hund's rule e xchange interaction between the d orbitals. Taking realistic parameter s deduced from band structure calculations and spectroscopic data, we obtained saturated ferromagnetism for Ni-13, Co-13, and Pd-13 clusters , while Rh-13 fcc and Ru-13 clusters are partially magnetic, with an a ntiferromagnetic orientation of the moments on the central atoms in Ru clusters. Our results for 4d transition-metal clusters agree qualitat ively with the recent experimental data and with other calculations. M etastable magnetic clusters were identified in several situations. We found a dependence of the equilibrium lattice constant on the magnetiz ation in the considered clusters which may be explained by the charact er of wave functions in the cluster electronic structure.