Low-Temperature Formation of the FePt Phase in the Presence of an Intermediate Au Layer in Pt/Au/Fe Thin Films
DOI:
https://doi.org/10.20535/1810-0546.2016.1.53939Keywords:
Magnetic recording, Film composition, FePt, Low-temperature homogenization, Chemical orderingAbstract
Background. Pt/Fe bilayers with L10-FePt phase are prospective candidates for applications in ultra-high density magnetic storage due to their strong magneto-crystalline anisotropy. Typically, the L10-FePt phase can be formed from the disordered A1 FePt phase after post-annealing or after epitaxial growth on suitable substrates at elevated temperatures. However, industrial application of these films requires low-temperature ordering as well as control of grain size and crystal orientation.
Objective. Investigation of the intermediate Au layer influence on the low-temperature diffusion phase formation processes in nanoscale film compositions Pt/Au/Fe.
Methods. The film compositions were deposited by magnetron sputtering;
the structural properties of the as-deposited and annealed films were analysed by x-ray diffraction method and secondary neutral mas-spectroscopy.
Results. It was shown by SNMS depth profiles and XRD measurements that the provision of additional Au layer leads to diffusion intermixing of Pt and Fe layers acceleration and to the formation of partially ordered L10-FePt phase.
Conclusions. The introduction of the additional intermediate Au layer leads to the enhancement of the low-temperature intermixing of nanocrystalline Fe and Pt thin films. The intermixing at relatively low temperatures is caused by the grain boundary diffusion induced reaction layer formation mechanism. At the same time the ordering is also enhanced, leading to the appearance of the chemically ordered L10 FePt phase, which results in a strongly increased coercive field. The enhanced chemical L10 ordering is interpreted by stresses developed during the formation of the disordered A1 FePt phase along the GBs: in some of the new grains formed, where there is compressive stress along the {001} direction, chemical ordering can take place.
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