Cold homogenization of Fe/Pt based layered thin films induced by diffusion processes

• Applicant: Professor Dr. Manfred Albrecht
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2017 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 370878165

Functional thin films play an important role in modern technologies such as in micro- and nano-electronics, which allowed great breakthroughs in their technological development. For different areas of thin film application, it is necessary to understand the physics of interaction and diffusion processes between different components of thin film heterostructures. One of the features of diffusion in thin films is the sufficient mass transport even at low temperatures given by the small diffusion distances and promoted by a high level of defects in these materials. Defects may induce strong diffusion enhancement and thus may lead to metastable phase formation, which do not correspond to any equilibrium state.The project proposal is devoted to diffusion processes in Fe/Pt based heterostructures during low temperature annealing forming the L10 ordered FePt phase with a specific microstructure. L10 ordered FePt thin films have attracted a lot of interest due to their excellent magnetic properties, including high magnetic anisotropy, leading to drastic increase of magnetic recording density in the case of application of this material as magnetic recording medium. In our study the L10 ordering formation will be promoted by different intermediate layers (X, both, showing non-miscibility in FePt alloy - Tb, C or forming ternary alloys - Mn). In this case, the diffusion process is dominated by grain boundary diffusion as bulk diffusion can be neglected. Based on directional diffusion processes even graded FePt magnetic thin films, where the magnetic properties vary within the layer stacks, can be realized.Special attention will be given to the impact of an applied external magnetic field during low temperature annealing. It is assumed that the magnetic field might influence the stage of nucleus formation, which in turn affects the L10 phase formation temperature and orientation. Furthermore, magnetostrictive effects might develop with alloy formation, which is expected to have a large impact on stress-induced ordering kinetics. These studies will be accompanied by molecular dynamic simulations in order to extract diffusion mechanisms on the atomic level.

• DFG Programme: Research Grants
• International Connection: Ukraine
• International Co-Applicant: Dr. Igor Vladymyrskyi