FePt Magnetic Nanoparticles and Their Assembly for Future Magnetic Media

Abstract

Magnetic nanoparticles with extremely high anisotropy such as chemically ordered L1 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> phase FePt nanoparticles have been considered one of the best candidates for future magnetic recording media with areal density beyond 1 Tbit/in <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> for either the nanocomposite-film-type heat-assisted magnetic recording (HAMR) media or the self-organized-magnetic-array (SOMA)-type bit patterned media. However, current preparation methods via phase transformation must overcome many obstacles, including particle agglomeration, twinning, and difficulty of easy axis alignment. In this paper, the effort on and promise of the preparation of monodispersed magnetic nanoparticles with high anisotropy by a gas phase condensation method is reviewed and reported. The focus is to review recent progress on the fabrication of monodispersed highly ordered L1 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> phase FePt nanoparticles without phase transformation, successfully self-assembled and magnetically aligned magnetic nanoparticles for SOMA and HAMR media. The mechanisms for directly forming L1 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> phase FePt nanoparticles during nucleation and growth processes and magnetically aligning these particles are analyzed.