Jagiellonian University in Krakow, Poland
Title: Chemical ordering phenomena in nanostructured FePt: Monte Carlo simulations
Biography: Rafal Abdank-Kozubski
Monte Carlo (MC) simulation studies of free-surface-induced selective destabilization of L10 superstructure variants in FePt
nanolayers, nanowires and nanoparticles were carried out. The system was modeled with nn and nnn interatomic pair interactions deduced from ab initio results for Fe-Pt. The heterogeneous nucleation of a- and b-L10 variant domains reported previously for FePt nanolayers was induced by the (100)-type surfaces limiting the nanostructures. While the initial c-variant L10 superstructure of nanowires transformed totally to the L10 a-variant with Fe and Pt monoatomic planes perpendicular to the wire axis and to both (010) and (001) surfaces, in the case of nanocubes the competition between the a- and b-variant L10 domains nucleating at the (100), (010) and (001) surfaces resulted in suppression of their growth. As a consequence, most of the cube volume remained untransformed and showed the c-variant L10 chemical long-range order (LRO) with a degree lowered by homogeneously creating antisite defects. The results quantified by the calculated a- and b-L10 domain penetration depth and the LRO and SRO degree in particular cases are important for the development of magnetic storage media technologies
requiring stable L10 superstructure variants determining easy magnetization directions.