Development of observation methods for nano-sized magnetic domains with electron holography

电子全息纳米磁畴观测方法的发展

• 批准号: 13555017
• 负责人: SHINDO Daisuke
• 金额: $ 8.45万
• 依托单位: Tohoku University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2003
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-13555017/
• 关键词: electron microscopy; magnetic domain structure; magnetic materials; electron holography; phase transformation; magnetic recording; image processing; microstructure; 磁性体; マンガン酸化物; 磁化分布; 磁壁; 磁束; 磁石材料; 微細組織; ホログラム; 磁場印加

The target of the present works is to develop a new technique of in situ observations with electron holography and apply the new techniques to studies of magnetic domains in advanced materials. The results are summarized as follws:1.A new apparatus with a small hall probe was developed, which enables us to measure the magnetic field inside the objective lens. This apparatus has revealed the relation between the magnetic field near the specimen and the electric current of the objective lens so that magnetic domains can be observed in a wide range of the applied magnetic field.2.Experimental conditions to observe electron holograms were optimized by operating the electromagnets installed in the electron microscope. Visibility of the holograms was much improved.3.A technique to separate the magnetic information in holograms from the electric information (the effect of mean inner potential) was established. The electric information can be eliminated by numerical analyses of two digitized holograms, which are obtained in magnetic and nonmagnetic states, respectively.4.The new techniques were applied to studies of magnetization distribution in a perovskite-type manganite, which exhibits the well-known colossal magnetoresistance. Distribution of magnetic flux was directly observed in a magnetically phase-separated state. The results shed light on understanding of the conduction mechanism of hole-doped manganites.

本工作的目标是发展一种新的电子全息原位观测技术，并将这种新技术应用于先进材料中磁畴的研究。1.研制了一种小型霍尔探头测量物镜透镜内部磁场的装置。该装置揭示了样品附近的磁场与物镜透镜电流之间的关系，从而可以在很宽的外加磁场范围内观察磁畴。2.通过操作电子显微镜中的电磁铁，优化了观察电子全息图的实验条件。提出了一种将全息图中的磁信息与电信息分离的方法（平均内电位效应）。通过对磁态和磁态的数字化全息图进行数值分析，消除了电信息的影响。4.将新技术应用于钙钛矿型锰氧化物的磁化强度分布研究，该材料具有庞磁电阻效应。在磁相分离状态下直接观察到磁通量的分布。研究结果为理解空穴掺杂锰氧化物的导电机理提供了理论依据。

项目成果

Y.Gao, D.Shindo: "Mediated exchange interaction in Fe-Nb-B nanocrystalline soft magnetic materials"Phys.Rev.B. 67. 172409(1)-172409(4) (2003)

Y.Gao，D.Shindo：“Fe-Nb-B 纳米晶软磁材料中的介导交换相互作用”Phys.Rev.B。

Y.Gao et al.: "Mediated exchange interaction in Fe-Nb-B nanocrystalline soft magnetic materials"Phys.Rev.B. 67. 172409-1-172409-4 (2003)

Y.Gao等：“Fe-Nb-B纳米晶软磁材料中的介导交换相互作用”Phys.Rev.B。

D.Shindo: "Characterization of a Co-CoO obliquely evaporoted magnetic tape by analytical electron microscopy and electron holography"Microscopy and Microanalysis. vol.10. 115-121 (2004)

D.Shindo：“通过分析电子显微镜和电子全息术表征 Co-CoO 倾斜蒸发磁带”显微镜和微量分析。

D.Shindo at al.: "Magnetic domain structure of Fe_3B/Nd_2Fe_<14>B nanocomposite magnets studied by electron holography"Proc. 15th Inter. Con. on Electron Microscopy. 735-736 (2002)

D.Shindo等人：“通过电子全息术研究Fe_3B/Nd_2Fe_14B纳米复合磁体的磁畴结构”Proc。

Y.Aoyama et al.: "Precise Evaluation of Charged Effect on SiO_2 Particles by Simulation of Holograms"Mater. Trans., 43(2002), in press.

Y.Aoyama等：“通过全息图模拟精确评估SiO_2颗粒的带电效应”材料。