LAUSR

Abstract The behavior of local magnetic moments and exchange coupling parameters of Fe x Co 1 - x nanostructures (nanowires and compact clusters) on the fcc Pt(1 1 1) surface is here investigated using the first-principles real-space RS-LMTO-ASA method, in the framework of the DFT. Different configurations of Fe x Co 1 - x trimers and heptamers on Pt(1 1 1) are considered, varying the positions and the concentration of Fe or Co atoms. We discuss the influence of dimensionality and stoichiometry changes on the magnetic properties, specially on the orbital moments, which are very important in establishing a nanoscopic understanding of delocalized electron systems. We demonstrate the existence of a strictly decreasing nonlinear trend of the average orbital moments with the Fe concentration for the compact clusters, different from what was found for Fe x Co 1 - x nanowires on Pt(1 1 1) and also for corresponding higher-dimensional systems ( Fe x Co 1 - x monolayer on Pt(1 1 1) and Fe x Co 1 - x bulk). The average spin moments, however, are invariably described by a linear function with respect to stoichiometry. In all studied cases, the nearest neighbors exchange couplings have shown to be strongly ferromagnetic.