兰州大学机构库 >物理科学与技术学院
坡莫合金薄膜中各种缺陷对磁化反转钉扎作用的Lorentz电子显微术研究
Alternative TitlePinning effect of various defects on the magnetization reversal processes in Permally films in-situ observed by a Lorentz TEM
马传生
Thesis Advisor王建波
2012-05-27
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name硕士
Keyword洛伦兹电子显微术 缺陷 钉扎 磁化反转 畴壁运动
Abstract理解并直接观测磁性材料在外磁场等外部因素下的磁化反转过程,是新型磁性器件的设计制作的关键环节之一。洛伦兹透射电子显微术因其具有超高的空间分辨率以及能够进行大范围实时观测等优点,成为目前观测样品磁特性较为常用的一种分析测试手段。 本文将详细介绍洛伦兹透射电镜的基本知识以及调试测试方法。并利用洛伦兹透射电镜,从缺陷的磁性、形状、位置等角度研究了碳膜孔洞、M型钡铁氧体、四氧化三铁颗粒、镍纳米线、氧化锡颗粒等缺陷对坡莫合金薄膜磁矩分布和磁化反转过程的影响,并得到以下结果与结论: (1)坡莫合金薄膜中块状的缺陷会使周围主磁矩方向上的磁矩沿着缺陷呈环状分布,并且该受缺陷影响的磁矩范围由两条类抛物线状小畴壁包围。 (2)缺陷对周围样品磁矩的影响与缺陷的几何性质和磁学性质都有关系。 (3)小角度引入物镜磁场将导致坡莫合金薄膜的一致连续磁化反转过程。大角度引入物镜电流将导致以畴壁运动来完成磁化反转的磁化过程。 (4)缺陷对畴壁运动的钉扎作用不仅仅局限于缺陷本身,缺陷所引起的扇形磁畴区也对畴壁的运动起着钉扎作用。 (5)畴壁在穿过缺陷的过程中,两者的小畴壁会发生合并,角色互换。
Other AbstractIn this thesis, the principles and critical operations of a Lorentz TEM will be introduced. Moreover, the distribution of magnetic moments surrounded various defects and the influence of different defects on the magnetic reversal in Permally alloy films were observed by the Lorentz TEM. The following findings and conclusions are achieved: (1) The block defects in Permalloy thin film cause a circle distribution of magnetic moment surrounded these defects. (2) The geometry and magnetic properties of the inserted defects influence the distribution of magnetic moments surrounded these defects. (3) A coherent and continuous reversal process occurs when the sample holder has been tilted a small angle. Whist, a domain wall motion happens when the sample holder has been tilted a large angle. (4) The domain wall motion has been pinned by not only defects themselves but also the fan-shaped region of magnetic moments formed by the defects. (5) The small domain walls located at the two sides of a main domain wall emerge together in the beginning and then swap each other when the domain walls pass through the inserted defects.
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Language中文
Document Type学位论文
Identifierhttps://ir.lzu.edu.cn/handle/262010/229490
Collection物理科学与技术学院
Recommended Citation
GB/T 7714
马传生. 坡莫合金薄膜中各种缺陷对磁化反转钉扎作用的Lorentz电子显微术研究[D]. 兰州. 兰州大学,2012.
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