Abstract Structural phase formation induced by thermally-activated diffusion processes and intermixing of layered structures is a promising reaction pathway for the synthesis of unexpected (metastable) thin film materials. Furthermore, the sequence of structural phase transitions during annealing can substantially differ from those predicted by corresponding bulk phase diagrams due to the underlying grain boundary diffusion mechanisms as well as surface and interface effects. In this study, phase transitions in Pt/Tb/Fe trilayers occurring during post-annealing up to 620°C were investigated by various techniques including x-ray diffraction, transmission electron microscopy, secondary neutral mass spectrometry, Auger electron spectroscopy depth profiling, and magnetic properties measurements. At an annealing temperature of 215°C pronounced Pt and Tb diffusion intermixing is observed leading to the formation of the binary Pt2Tb phase. Further annealing up to 280 °C is accompanied by the appearance of the chemically disordered A1-FePt phase and significant Tb segregation to the outer surface forming an oxide layer. The chemically ordered L10-FePt phase starts to form in parallel to the disappearance of the Pt2Tb phase at 450°C. The final phase product at 620°C is characterized by the coexistence of two remaining phases, L10-FePt and TbO2. Structural phase transitions have a significant impact on the films magnetic properties – heat treatment leads to an enhancement of the coercive field. This fact is associated with the formation of the hard magnetic L10-FePt phase, which might be accompanied by grain isolation induced by partially Tb/Tb-O grain boundary filling.

中文翻译：

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Pt/Tb/Fe 三层中的热致相变

摘要 由热活化扩散过程和层状结构的混合引起的结构相形成是合成意想不到的（亚稳态）薄膜材料的有前途的反应途径。此外，由于潜在的晶界扩散机制以及表面和界面效应，退火过程中的结构相变序列可能与相应体相图预测的相变序列大不相同。在这项研究中，Pt/Tb/Fe 三层在高达 620°C 的后退火过程中发生的相变通过各种技术进行了研究，包括 X 射线衍射、透射电子显微镜、二次中性质谱、俄歇电子能谱深度分析和磁特性测量。在 215°C 的退火温度下，观察到明显的 Pt 和 Tb 扩散混合，导致形成二元 Pt2Tb 相。高达 280 °C 的进一步退火伴随着化学无序的 A1-FePt 相的出现和显着的 Tb 偏析到外表面，形成氧化层。化学有序的 L10-FePt 相开始形成，同时 Pt2Tb 相在 450°C 消失。620°C 下的最终相产物的特征是两个剩余相 L10-FePt 和 TbO2 共存。结构相变对薄膜的磁性能有显着影响——热处理导致矫顽场增强。这一事实与硬磁 L10-FePt 相的形成有关，