Smart Materials & Structures

Biography

Biography: Rafal Abdank-Kozubski

Abstract

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.