【作者】 庞智勇；

【导师】 韩圣浩；

【作者基本信息】 山东大学 ， 微电子学与固体电子学， 2006， 博士

【摘要】 磁性材料在电工技术，计算机技术，通讯技术以及最近兴起的自旋电子学等领域具有重要的应用。技术上的应用对材料性能提出进一步的要求，这反过来进一步推动了磁学和磁性材料的研究。我们知道，磁性材料的性能与其微观晶体结构和磁畴结构紧密相关，研究材料的磁畴结构不仅有助于了解材料本身的磁化和反磁化机理，了解矫顽力机制，而且对改进材料生产工艺，进而改善磁性能也都是非常重要的。观察磁畴的技术方法有很多种，其中最有力的工具就是磁力显微镜，它具有高的空间分辨率（10-50nm），不需要特殊的样品制备，并可以测量不透明及有非磁覆盖层的样品，可以在任意的环境中工作，操作比较简单，采图任意，适用的磁性材料的范围也很广，由于具有上述优势，使得磁力显微镜一经出现，就成为应用最广泛的磁畴观察工具。 本论文主要包括两部分的工作：第一部分主要是纳米磁性材料表面微结构与磁畴结构的测量与表征。包括：（1）利用磁力显微镜研究了三种不同材料的微晶结构和磁畴结构，分析了微晶结构和磁畴结构与其磁性的关系，讨论了其矫顽力机制，分析了其磁性变化的原因；（2）为加深对磁力显微镜成像原理的了解，并为分析纳米颗粒的磁畴图形提供理论参考，进行了单畴亚微米磁性颗粒的磁力显微镜图形的计算机模拟和一些亚微米磁性结构的微磁学模拟；（3）对新型高分辨成像技术进行了初步探索。除了上述关于材料的性能与表征的研究以外，我们还进行了一些自旋极化载流子注入有机半导体方面的探索，作为论文的第二部分。具体的研究内容和基本结果如下： 1、首次利用磁力显微镜直接在铜模吸铸法获得的直径为5mm的Pr₆₀Al₁₀Ni₁₀Cu_20-xFe_x（0≤x≤20）棒状合金圆柱侧表面观测了其制备态的表面形貌结构和相应的磁畴结构。发现随着Fe掺杂量的增加，样品从完全非晶结构转变为纳米晶非晶镶嵌结构，然后随着铁掺杂量的继续增加，转变为完全纳米晶结构。伴随着样品的磁性从顺磁性转变为硬磁性。在Fe含量大于10at％的样品的表面形貌图和相更多还原

【Abstract】 Magnetic materials have been employed in a truly wide range of applications such as electrical engineering, computer science, communication technology, and spintronics arisen in recent years. The development of applications requires materials with higher performance, which in turn accelerates the development of magnetism and magnetic material research. As is well known, the performance of magnetic materials is tightly related to their crystalline and magnetic microstructures. Therefore, it is of great significance to investigate their crystalline and magnetic microstructures and their correlation with material performance. Furthermore, magnetic domain research is also helpful to understand their magnetization reversal behavior and coercivity mechanism, sequentially ameliorate their manufacture technics and improve their performance. Among all magnetic sensitive imaging techniques, magnetic force microscope （MFM） is a very powerful instrument to investigate the crystalline and magnetic microstructures of magnetic materials due to its high lateral resolution （10-50 nm）, low sample preparation quality requirement, simple operation, and wide range of materials applicable. Furthermore, it can capture the crystalline microstructure images and corresponding magnetic microstructure images simultaneously. These advantages make MFM the most widely used magnetic domain observation technique soon after its invention.In this thesis, crystalline and magnetic microstructures of three series of magnetic materials named Pr_yFe_90-yB₁₀ （y=8.0～11.76）, Pr₆₀Al₁₀Ni₁₀Cu_20-xFe_x （0≤x≤20） and La_0.7Sr_0.3Fe_11.8Co_0.2O₁₉ （at.%） are investigated using MFM. The correlation between their crystalline and magnetic microstructures and their magnetic performance is detailedly discussed and their coercivity mechanisms are also analyzed. To further understand the imaging principle of MFM and provide theoretical reference for MFM image analysis of magnetic nanoparticles, computer simulation of MFM images and domain structure of sub-micron magnets is also performed. Besides, explore for new magnetic sensitive imaging technology with ultra-high resolution has also been tried. At last, the injection, transport and detection of spin dependent carriers in organic更多还原