Structures and magnetic properties of oriented Fe/Au and Fe/Pt nanoparticles on a-Al2O3
- 1 January 1999
- journal article
- Published by Oxford University Press (OUP) in Journal of Electron Microscopy
- Vol. 48 (6) , 753-759
- https://doi.org/10.1093/oxfordjournals.jmicro.a023745
Abstract
Granular thin films of oriented a-Fe nanoparticles on a-Al2O3 were fabricated by electron beam evaporation technique. The process took advantage of the overgrowth of α-Fe on Au or Pt ‘seed’ particles epitaxially grown on (100) NaCl substrates, which were later removed in distilled water. The crystallographic orientation between α-Fe and Au (Pt) nanocrystals was Au(Pt)//Fe with {010}Au(Pt)//{010}Fe The magnetic coercivity of the oriented α-Fe particles was controllable by particle size and inter-particle distance. Annealing of the a-Al2O3/Fe/Pt films at temperatures higher than 500°C led to a formation of the ordered Ll0-FePt phase. Any one of the three axes of the fcc parent phase acted as the tetragonal c-axis of the Ll0 superstructure. Magnetic coercivities of a-Al2O3/Fe/Pt films were found to be largely increased by heat treatment. The coercivity of the annealed a-Al2O3/Fe/Pt films reached as high as 3.5 kOe with a squareness of 0.74. It has been shown that magnetic property can be improved by controlling orientation and structure of the magnetic particles.Keywords
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