Synthesis of single-crystal Sm-Co nanoparticles by cluster beam deposition
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Single-crystal Sm-Co nanoparticles have been successfully produced by a cluster beam deposition technique. Particles have been deposited by DC magnetron sputtering using high Ar pressures on both single-crystal Si substrates and Au grids for the magnetic and structural/microstructural properties, respectively. Oxidation of the particles is prevented by using carbon buffer and cover layers. Nanoparticles have a uniform size distribution with an average size of 4.2, 6 and 7 nm at 1, 1.5 and 2 Torr of Ar pressure, respectively. At 1 Torr, the particles have the disordered 1:7 structure and a high coercivity of 19 kOe at 10 K. These particles show a superparamagnetic behavior with a blocking temperature of TB = 145 K. From this value of TB and the particle volume, the value of anisotropy constant K is estimated to be around 2.2 × 107 ergs/cc. Heat is introduced to the particles during their flight to the substrate to increase the particle size. Nanoparticles of SmCo5 with an average size of 15 nm and high room temperature coercivity have been produced. No change in magnetic and structural properties of the samples has been observed even after 10 months. Cluster beam deposition could play a key role for the production of rare earth nanoparticles for many applications.
KeywordsSputtering Coercivity Nanoparticles Sm-Co Rare earth metals
The authors would like to thank A. M. Gabay for helpful discussions. The authors also thank Dr. Melania Marinescu and EEC for providing the targets. Work supported by DOE DE-FG02-04ER4612.
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