条纹畴结构金属薄膜的微波高磁导率机制

This project is aimed to research the mechanism of realizing high permeability in GHz range in any direction within the metallic thin film plane. The key point is to manipulate the strip domain structure which formed in the thin films of Fe and Co based alloys. Thin films with different amounts of doping and thicknesses will be fabricated by radio-frequency sputtering, and the preparation parameters can be obtained based on the study of their structure and morphology. The formation conditions and characteristics of the strip domain structure could be investigated by comparing the intrinsic and technological magnetic properties which are obtained from the macro- and micro- magnetic measurements. Special attention will be paid on effective measures to reorient the direction of the strip domain structure by DC magnetic field. The dependence of GHz permeability vs. frequency can be obtained by using the vector network analyzer, and the relationship between the permeability and the strip domain structure can be derived further. The dynamic process and picture of the magnetization under GHz microwave in strip domain structure can be explored by spin rectification enabled by magnetic resistance or abnormal Hall effect, and the nature of the high permeability of the thin films at GHz will be discussed. Combining the above results, the mechanism of high permeability in GHz range of the thin films with strip domain structure can be studied. The outcomes of this project will provide both theoretical and technological gist for fabrication of the micromation and integration inductor-like electronic devices with high microwave sensitivity.

本项目以探索金属薄膜面内任意方向均可实现GHz高磁导率的机制为目的，以控制金属薄膜的条纹畴结构为关键，以高饱和磁化强度的Fe、Co基合金为载体展开研究。拟用射频溅射技术制备不同元素掺杂和不同厚度的Fe、Co基合金薄膜，结合结构和形貌观测，掌握不同成份和厚度的金属薄膜制备工艺。通过宏观和微观磁测量，掌握薄膜的内禀和技术磁性，探索薄膜磁化强度形成条纹畴结构分布的条件，以及条纹畴结构的特征，尤其是条纹畴方向的直流磁场调控特点。利用矢量网络分析仪获得金属薄膜的GHz磁导率随频率的变化，构建磁导率与条纹畴结构的关系。利用磁电阻或异常霍尔效应的自旋整流效应获得条纹畴结构中磁化强度在GHz下的动力学过程和图像，探索条纹畴结构薄膜GHz高磁导率的本质。结合以上数据，获得实现金属薄膜面内任意方向GHz高磁导率的机制，为360度高灵敏度的高频化、微型化和集成化电感类电子器件的制备提供理论和技术依据。

本项目围绕金属薄膜面内任意方向均可实现GHz高磁导率的机制，以控制金属薄膜的条纹畴结构为关键，以高饱和磁化强度的Fe、Co基合金为载体展开研究，取得了系统性的研究成果。在多个金属薄膜体系上，实现了对薄膜各向异性的调控，实现了金属薄膜条纹畴结构，获得了条纹畴结构的微波高磁导率机制：翘出膜面各向异性决定了条纹畴的形成，而面内各向异性决定了面内可转动高磁导率特征。探索了磁化强度动力学高频高磁导率的本质：高翘出面外各向异性和低面内各向异性，提出了面内转动各向异性的重要性：决定了面内任意方向的高磁导率。利用光学支共振，提出并实现了超越声学支工作频率下的正磁导率。发现了四个在面内任意方向上实现5 GHz以下磁导率大于10的磁性金属薄膜体系：条纹畴结构薄膜、A/B/A三层膜结构、准单畴结构面内转动各向同性薄膜以及无交换偏置的反铁磁耦合铁磁薄膜。尤其是A/B/A（A为铁磁层，B为非磁性层）三层膜结构实现了真正面内各向同性高磁导率，对于电感类器件的集成化具有重要意义。构建了两种磁化强度动力学测试系统：室温—200ᵒC薄膜变温磁谱测试系统，10-300 K整流测试系统。对于从磁性和电性测试认识高频磁性以及薄膜的温度稳定性具有现实意义。本项目发表标注国家自然科学基金资助SCI论文38篇，获批国家发明专利6件。培养本科毕业生5名，硕士研究生5名，博士生5名，博士后1名。