Nanocomposites and nanomaterials
Formation of ordered L10 FePt phase in Pt/Ag(Au)/Fe and Fe/Ag(Au)/Pt trilayers
Makushko P.V1, Schmidt N.Yu2, Verbytska T.I.1, Katona G.3, Beke D. 3, Albrecht M.2, Makogon Iu.M.1
1 National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”, Prospect Peremogy 37, Kiev 03056, Ukraine. 
E-mail: email.of. corresponding_verbitska@kpm.kpi.ua
2 Institute of Physics, University of Augsburg, Universitätstrasse 1, 86135 Augsburg, Germany.
3Department of Solid State Physics, Faculty of Sciences and Technology, University of Debrecen, P.O. Box 400, H-4002 Debrecen, Hungary.

In HAMR (Heat Assisted Magnetic Recording) technology at the manufacture of a medium for magnetic recording it is important to create layers with different magnetic hardness. The intermediate layers are necessary in recording media design because they induce textured growth in the recording layer and improve the exchange decoupling between the magnetic grains.
In this work the diffusion formation of an ordered L10 FePt phase in Pt(15 nm)/Ag(Au)/Fe(15 nm) and Fe(15 nm)/Ag(Au)/Pt(15 nm) trilayers with Ag(Au) interlayer thickness of 10 nm is studied. 
The films were prepared by magnetron sputtering on SiO2/Si(001) substrate. Isothermal annealing of the tri-layered samples were carried out in a vacuum of 1,3·10-3 Pa at temperature of 700 °С for 30 s, 2 min, 5 min, 15 min and 30 min. The structural properties of the as-deposited and annealed films were characterized by X-ray diffraction. Depth profiles of the films were investigated by secondary neutral mass spectrometry. The magnetic properties were determined by a superconducting quantum interference device (SQUID).
It was found that by changing the sequence of Fe or Pt layers deposition it is possible to form the soft magnetic and hard magnetic layers due to directed Ag(Au) diffusion, creating a heterogeneity of the chemical composition along the film thickness. 
This work was financially supported by the German Academic Exchange Service (DAAD) in the frame of Leonard Euler scholarship program Grant ID 57198300.