Synthesis of FePt nanocubes and their oriented self-assembly.

Monodisperse FePt nanocubes are synthesized at 205 degrees C by controlling decomposition of Fe(CO)5 and reduction of Pt(acac)2 and addition sequence of oleic acid and oleylamine. Different from the assembly of the sphere-like FePt nanoparticles, which shows 3D random structure orientation, self-assembly of the FePt nanocubes leads to a superlattice array with each FePt cube exhibiting (100) texture. Thermal annealing converts the chemically disordered fcc FePt to chemically ordered fct FePt, and the annealed assembly shows a strong (001) texture in the directions both parallel and perpendicular to the substrate. This shape-controlled synthesis and self-assembly offers a promising approach to fabrication of magnetically aligned FePt nanocrystal arrays for high density information storage and high performance permanent magnet applications.