Nanoscale physics
Structural phase transformations in annealed Pt/Mn/Fe trilayers
I.O. Kruhlov1, N.Y. Schmidt2, S.I. Sidorenko1, G.L. Katona3, M. Albrecht2, and I.A. Vladymyrskyi1
1 Metal Physics Department, National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”, Prospect Peremogy 37, 03056 Kyiv, Ukraine
E-mail: vladymyrskyi@kpm.kpi.ua
2 Institute of Physics, University of Augsburg, Universitätsstraße 1, D-86159 Augsburg, Germany
3 University of Debrecen, Faculty of Science and Technology, Department of Solid State Physics, P.O. Box 400, H-4002 Debrecen, Hungary

The sequence of thermally-activated phase transitions in Pt(15 nm)/Mn(7.5 nm))/Fe(15 nm) thin films was investigated by a combination of x-ray diffraction, transmission electron microscopy, secondary neutral mass spectrometry depth profiling, atomic force microscopy, and magnetic properties measurements. Post-annealing was carried out in vacuum to different temperatures up to 620 °C. Initially, in temperature range from 280 °C to 450 °C first L10-MnPt phase is formed at the Pt/Mn interface followed by the most likely formation of metastable bcc-Fe3Pt, which gets transformed by further annealing to fcc-Fe3Pt and eventually to chemically ordered L12-Fe3Pt. The final product after annealing at 620 °C consists of two interesting phases, which are relevant for spintronic applications, antiferromagnetic L10-MnPt with addition of Fe and ferromagnetic L12-Fe3Pt, consistent with the initial element composition. The final phases content is consistent with the initial elemental concentrations of the Pt/Mn/Fe trilayer, however the path of synthesis was rather unexpected.