Structures and Magnetic Properties of Mo-Doped Palladium Clusters

The structural evolution and magnetic properties of MoPdn (n = 2-14) clusters have been investigated using the density functional theory. Extensive search of the lowest-energy structures has been conducted by considering a number of structural isomers for each cluster size. In the lowest energy structures of MoPdn clusters, the Mo atom gradually moves from an extruded vertex site, to a surface, and to an interior site as the number of Pd atoms increases from 2 to 14. The electronic structures and magnetic properties of MoPdn clusters are investigated. We find that the magnetic moments of Pd-n clusters have been enhanced by the doping of Mo impurity for the small sizes of n <= 6. Larger MoPdn clusters with n >= 7 are completely nonmagnetic. The quenching of the magnetic moment comes from the electronic and geometric effects for MoPdn clusters. Furthermore, the magnetic properties of 3d and 4d transition-metal (TM) atoms doped in the chosen sizes palladium clusters (Pd-9 and Pd-12) are studied. The magnetic moments for most 3d and 4d TM atoms are completely quenched by the palladium hosts, while the magnitudes of the remaining moments for Mn, Fe, Co, Ni, Rh, and Pd impurities are significantly reduced from those of free atoms. The significant reduction or complete quenching of magnetism can be understood by the hybridization between the doped TM atom and its neighboring Pd atoms.