Nanocomposites and nanomaterials

Diffusion and diffusion-driven local ordering in Co-Pt thin films 
Pedan R.1, Makushko P.1,2, Dubikovskyi O.1,3, Bodnaruk A.1,4, Burmak A.1, Makarov D.2, Vladymyrskyi I.1
1 Igor Sikorsky Kyiv Polytechnic Institute, Prospect Peremogy 37, Kyiv 03056, Ukraine. E-mail: roman1pedan@gmail.com
2 Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Ion Beam Physics and Materials Research, Bautzner Landstrasse 400, 01328 Dresden, Germany.
3 V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine, Prospect Nauky 41, Kyiv 03680, Ukraine.
4 Institute of Physics, National Academy of Sciences of Ukraine, Prospect Nauky 46, Kyiv 03028, Ukraine.

Co-Pt based alloys are perspective materials for spintronics and data storage applications [1]. Thus, investigation of diffusion and diffusion-controlled formation of the ordered magnetic phases in Co/Pt-based thin films is of practical relevance [2].
In this work, magnetron deposited layered stacks of Pt(14 nm)/Co(13 nm)/Ta(3 nm) were annealed in high vacuum in the temperature range of 200 °С – 550 °С. The structure, chemical composition and magnetic properties of the post-annealed stacks were analyzed by chemical depth profiling, X-ray spectroscopy, scanning transmission electron microscopy, x-ray diffraction, and VSM magnetometry.
We demonstrate that although the formation of a long-range chemical order in the CoPt film was not achieved, heat treatment leads to an increase in the coercive field and the formation of local anisotropy in the Co-Pt alloy.
The results of our work show the relevance of further studies of diffusion processes and the formation of hard magnetic phases via diffusion induced grain boundary migration mechanism in Co-Pt thin films during low-temperature annealing. 

1.	Mohapatra J., Xing M., Elkins J., Liu J.P. Hard and semi-hard magnetic materials based on cobalt and cobalt alloys // J. Alloys Compd.-2020.-824.-P. 153874.
2.	Liscio F., Maret M., Meneghini C., Mobilio S., Proux O., Makarov D., Albrecht M. Structural origin of perpendicular magnetic anisotropy in epitaxial CoPt3 nanostructures grown on WSe2(0001) // Phys. Rev. B.-2010.-81.-P. 125417.