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

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 x 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. (C) 2003 Elsevier B.V. All rights reserved.