We report the direct preparation of monodispersed L 10 phase FePt nanoparticles by controlled nucleation and growth using a gas phase aggregation source. These FePt nanoparticles became ordered during their growth in an argon gas flow. They are octahedron faceted with an average size of 5.8 nm and a standard size distribution of 11%, as illustrated by transmission electron microscope. Magnetic measurements show that these FePt nanoparticles have coercivities of 8.25 kOe at room temperature and 26.5 kOe at 50 K. This technique provides a novel approach for fabricating nanomaterials with controllable phase and shape in general.
Bibliographical noteFunding Information:
This work was performed as part of the Information Storage Industry Consortium (INSIC) program in Heat Assisted Magnetic Recording (HAMR), with the support of the U.S. Department of Commerce, National Institute of Standards and Technology, Advanced Technology Program, Cooperative Agreement No. 70NANB1H3056. The authors thank Heraeus Corp. for partial financial support, Professor C. Leighton for the usage of SQUID, Dr. S. Mckernan for his help on high-resolution TEM work, and Dr. J. Bai and Y. Xu for useful discussion. The integrated nanoparticle deposition system used in this work was set up through one of the authors (J.P.W.) faculty startup fund from the University of Minnesota.