Magnetoanisotropy, long-range order parameter and thermal stability of isolated L10 FePt nanoparticles with mutual fixed orientation

Abstract

Oriented L1 0 -FePt nanoparticles with mean sizes as small as 12 nm have been fabricated by electron beam evaporation. Atomic order parameter evaluated was as low as 0.55±0.02 in spite of the long-time annealing as long as 86.4 ks at 873 K. Magnetoanisotropy constant was estimated to be 1.2–1.4×10 6 J/m 3 , which was much smaller than that of bulk FePt. Residual magnetization showed a decay of about 3–4% at 300 K. The relatively small values of magnetoanisotropy are closely related to the small order parameter, and thought to be responsible for residual magnetization decay at 300 K.