Electron microscopy study of L1(0)-FePtCu nanoparticles synthesized at 613K.

Finely dispersed hard magnetic L1o-FePtCu nanoparticles with 100 orientation were directly synthesized by RF-sputtering on NaCl substrate at a temperature of 613 K. The maximum coercivity of the particles was 1.4 kOe (at RT). Degrees of atomic long-range order (LRO) for the L1o-FePtCu nanoparticles with different sizes were obtained using nanobeam electron diffraction technique. The decrease of LRO parameter became remarkable when the size became below 8 nm. The coercivity value also decreased with decreasing the particle size. The relation between the LRO parameter decrease and the coercivity decrease with particle size was discussed.