Phys. Rev. B 79, 014414 (2009) [13 pages]Growth and magnetic characterization of Co nanoparticles obtained by femtosecond pulsed laser depositionReceived 10 February 2008; revised 1 December 2008; published 12 January 2009 We present a detailed study on the morphology and magnetic properties of Co nanostructures deposited onto oxidized Si substrates by femtosecond pulsed laser deposition. Generally, Co disks of nanometric dimensions are obtained just above the ablation threshold, with a size distribution characterized by an increasingly larger number of disks as their size diminishes, and with a maximum disk size that depends on the laser power density. In Au/Co/Au structures, in-plane magnetic anisotropy is observed in all cases, with no indication of superparamagnetism regardless of the amount of material or the laser power density. Magnetic force microscopy observations show coexistence of single-domain and vortex states for the magnetic domain structure of the disks. Superconducting quantum interference device magnetometry and x-ray magnetic circular dichroism measurements point to saturation magnetization values lower than the bulk, probably due to partial oxidation of the Co resulting from incomplete coverage by the Au capping layer. © 2009 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevB.79.014414
DOI:
10.1103/PhysRevB.79.014414
PACS:
75.75.+a
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