Shamis O V, Safonova N Y, Voron M M, Burmak A P, Sidorenko S I, Katona G L, Gulyas S, Beke D L, Albrecht M, Vladymyrskyi I A
Metal Physics Department, National Technical University of Ukraine 'Igor Sikorsky Kyiv Polytechnic Institute', Prospect Peremogy 37, 03056 Kyiv, Ukraine.
J Phys Condens Matter. 2019 Jul 17;31(28):285401. doi: 10.1088/1361-648X/ab169c. Epub 2019 Apr 5.
X-ray diffraction (XRD), secondary neutral mass spectrometry (SNMS) depth profiling, and electrical resistivity measurements were used to follow the phase transformations in Pt/Fe bi-layered thin films during annealing. Initially, the electrical resistivity increases linearly with temperature up to 150 °C due to the contribution of phonon scattering of the metallic Pt and Fe bilayer. Further increase of the annealing temperature leads to a steeper linear increase, which is associated with the initial formation of the chemically disordered A1-phase followed by the formation of the chemically ordered L1-FePt phase, as confirmed by XRD and SNMS studies. Finally, at about 620 °C the single L1-FePt phase has formed throughout the film. Moreover, the electrical resistivity contains also the magnetic contribution to the total resistivity. In this case, the loss in magnetic order is indicated by a change in temperature dependence of the resistivity at about 310 °C, representing the Curie temperature of the initially formed A1-FePt alloy, while the finally formed L1-FePt alloy reveals a higher magnetic transition temperature of about 410 °C. In this study, it has been demonstrated that resistometry in combination with structural and chemical analysis provides valuable information on diffusion processes, structural phase formations and its stability range, as well as on the magnetic transition temperature.
利用X射线衍射（XRD）、二次中性质谱（SNMS）深度剖析和电阻率测量来跟踪退火过程中Pt/Fe双层薄膜的相变。最初，由于金属Pt和Fe双层的声子散射作用，电阻率在温度升至150°C时随温度线性增加。退火温度的进一步升高导致线性增加更陡，这与化学无序的A1相的初始形成有关，随后是化学有序的L1-FePt相的形成，XRD和SNMS研究证实了这一点。最后，在约620°C时，整个薄膜中形成了单一的L1-FePt相。此外，电阻率还包含对总电阻率的磁贡献。在这种情况下，在约310°C时电阻率温度依赖性的变化表明磁有序的损失，该温度代表最初形成的A1-FePt合金的居里温度，而最终形成的L1-FePt合金显示出约410°C的更高磁转变温度。在本研究中，已证明电阻测量与结构和化学分析相结合可提供有关扩散过程、结构相形成及其稳定性范围以及磁转变温度的有价值信息。
