Effect of size and dimensionality on the magnetic moment of transition metals

The effect of size and dimensionality on the magnetic moments of Fe, Co, and Ni have been studied theoretically by confining the atoms t o various structural forms such as chains,surfaces, and thin films. The size of these systems is controlled by limiting t h e number of atoms. A new first-principles theory is developed that enables us to study the electron spin density of states and moments of atoms in clusters containing two to a few thousand atoms. The theory is based upon t h e elementary principles governing t h e tight binding and linear combination of atomic orbitals formulations. It contains no adjustable parameters and can be applied to systems with or without topological symmetry. We have discovered quantum size effects on t h e magnetic moments of linear chains and these effects disappear when the chains contain more than 20 atoms. We have also found distinct effects of the local environment on the magnetic moment. For example, t h e moments increase with decreasing coordination number and increasing interatomic distance. Our results will be compared with available experimental and theoretical results.