The Growth and Annealing of FePt Nanoparticles in the Presence of Magnetic Field

L1₀–FePt compound ordering phase formation in FePt nanocrystals needs high temperatures, which disagree with the nanostructural order. This means collective disordering of nanoparticles is the cost of the formation of internal ordering of nanoparticles. From the factors reported for the simultaneous presence of external and internal orders of FePt nanoparticles, applying elements, such as Ag and Cu in the compound and CoAg and MgO sublayers, can be mentioned. In this work, the effect of magnetic field on the formation of a L1₀–FePt orientational nanostructure has been investigated. In this case, XRD peaks relative intensity shows that such orientation forms in magnetic fields more intensive than a threshold magnetic field of 25 (mT) during cooling from 600 °C. Moreover, the presence of such external field through the growth of nanoparticles and their annealing stage disagrees with L1₀ phase formation and as a result, the amount of nanoparticles magnetic coercivity would be the result of the competition between magnetic field and temperature.