American Institute of Physics, Journal of Applied Physics, 9(107), p. 09B508
DOI: 10.1063/1.3368725
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Co–W nanoparticles formed by sequential sputtering of Co on amorphous alumina substrate and subsequent W capping are studied by high resolution and by scanning transmission electron microscopies, and by superconducting quantum interference device magnetometry. The analysis is focused on W nominal thickness dependence. Results suggest the formation of amorphous Co–W alloy nanoparticles, whose magnetic moment per Co atom is systematically reduced as the nominal thickness of W capping layer increases. The Co–W nanoparticles show superparamagnetic behavior. The activation energy for moment reversal and the effective anisotropy are obtained.