Fabrication and electron holography characterization of FePt alloy nanorods

Well-aligned, ferromagnetic FePt nanorods have been fabricated by electron beam-induced deposition using an ultrahigh-vacuum scanning electron microscope. A mixture gas of iron pentacarbonyl and cyclopentadienylplatinum (IV) trimethyl was used as a precursor and post-annealing at 600 °C for 2 h was performed to accomplish the crystallization process. Each nanorod was composed of a chain of crystalline Fe-Pt alloy nanoparticles encapsulated within a carbon-containing sheath. The nanoparticles were identified to be face centered tetragonal (fct) FePt phase (L 10, P4mmm) by electron diffraction and high-resolution transmission electron microscopy (HRTEM). The residual magnetic flux density Br of the nanorods was evaluated to be about 1.53 T via off-axis electron holography, showing a strong ferromagnetic character.