Magnetism of Rh-N clusters

The size and structural dependence of the magnetic properties of Rh-N clust ers (3 less than or equal to N less than or equal to 27) are studied by usi ng a d-electron tight-binding Hamiltonian which includes hybridizations, Co ulomb interactions, and spin-orbit coupling on the same electronic level. W e show that the spin (S) and orbital (L) magnetic moments depend strongly o n the local environment of the atoms and that their behavior as a function of the cluster size present oscillations which are in good qualitative agre ement with experiment. The magnetic anisotropy energy and the anisotropy in L are quantified by considering different directions of the spin magnetiza tion S within the cluster. We conclude that orbital contributions to the av erage magnetization in Rh-N clusters could be important for precise compari son with experiment. Bond-length relaxation effects are also briefly discus sed. (C) 2000 American Institute of Physics. [S0021-8979(00)30208-0].