Direct Preparation of Highly Ordered$rm L1_0$Phase FePt Nanoparticles and Their Shape-Assisted Assembly

Chemically ordered
$ L1_0$
phase FePt nanoparticles has been considered one of the best candidates for future magnetic recording media with areal density beyond 1 Tbit/in
$^2$
. 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 direct preparation of
$ L1_0$
phase FePt nanoparticles without phase transformation and particles' aqueous phase self-assembly are reported. The mechanism for
$ L1_0$
phase formation during nucleation and growth processes are discussed. The unique octahedron shape makes these highly ordered FePt nanoparticles even better choice for advanced magnetic recording media because they tend to form tilted and patterned media simultaneously due to the shape effect.