Ordering and Curie temperatures of FePt nanoparticles

The analytic models for size-dependent ordering and Curie temperatures of FePt nanoparticles have been proposed in terms of the size-dependent melting temperature. It is found that the order-disorder transition temperature TO and Curie temperature TC decrease with decreasing of the particle size D and the drop becomes dramatically once the size decreases to about 3 and 6 nm below for TO and TC, respectively. Moreover, the suppression of TC (D) is nearly twice as large as that of TO (D) when D is large enough. The accuracy of the developed model is verified by the recent experimental and computer simulations results.