Magnetic properties of fcc Co clusters: The role of internal defects

We report extensive self-consistent electronic structure calculations in order to analyze the influence of stacking fault like defects on the magnetic properties of fee Co clusters. The local orbital moments L(i) and the magnetic anisotropy energy (MAE) are found to be very sensitive to the size and structure of the systems while the local spin moments S(i) are saturated (∼1.7 μB), being almost independent of the direction of the magnetization δ, the local atomic environment i, and the size of the particles, a behavior that is characteristic of magnetic materials in the large exchange regime. We found that the local interruption of the regular growth mode in fee nanocrystals considerably perturbs the electron spin-density distribution around the defect sites, leading to strong variations in Lδ(i) and to reorientations of the magnetization in the system.

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