First-principles studies on magnetism of Ni clusters coated and alloyed with Pd

First-principles electronic-structure calculations are performed for the Ni clusters coated and alloyed with Pd. For coated clusters, the magnetic moments of the Ni core are reduced as compared to the bared one. Especially, Ni₁Ni₁₂Pd₆Pd₂₄Pd₁₂ cluster with O(h) symmetry consists of the ferromagnetic Ni core, the ferromagnetic Pd and paramagnetic Pd shells, the induced magnetic moment of Pd in the interface is 0.1μ(B), qualitatively in agreement with experimental results found in Ni particles coated with Pd. The dependence of magnetic moment on Pd thickness displays an oscillatory behavior, similar to that found in Co clusters coated with Cu or Ag and in Ni/Pd multilayers. For the alloyed clusters, the enhanced magnetism is confirmed, and the mechanism is clarified: which is resulted not only due to the large atomic distance of Pd but also due to electron transfers. The explanations are given for the different magnetic behaviors between coated and alloyed clusters. (C) 2000 Published by Elsevier Science B.V.