应学院彭勇教授邀请，中科院宁波材料所中科院夏卫星研究员将于2013年11月25日到27日间来我校访问并讲学，敬请关注！ 报告题目：Application of Lorentz microscopy and electron holography on magnetic materials

报告时间：2013年11月26日（星期二）下午4:00

报告地点：校本部格致楼5004室

报告摘要:

Nanocrystalline magnetic materials have attracted considerable attention because of their excellent magnetic properties. In order to clarify the coercivity mechanism and improve their magnetic properties, not only the crystallographic microstructures but also the micro magnetic domain structures are necessarily investigated. Recently, dipolar magnetism in self-assembled magnetic nanoparticles has been widely discussed. Electron holography is the unique technology that can detect the magnetic field distribution inside the specimen on nanometer scale, in combination with Lorentz microscopy, they have become indispensible ways for characterization of magnetic nanomaterials.

In our institute, a transmission electron microscope (TEM) JEM-2100F with a field emission gun has been installed to carry out research on magnetic materials. A special objective lens is designed to decrease the magnetic field at the specimen position to less than 10 Oe. An electron biprism is installed to carry out electron holography observation. The instrument can also implement in-situ experiment, i.e. applying an in-plane field inside TEM by a special holder with strength up to 400 Oe. This is the first TEM of its kind in China. With electron holography we have successfully observed the vortex domain structure of amorphous FeSiB disk, and quantitatively determined the core region where the spins orient vertically. We also observed the change in domain structures of perpendicular YIG thin film with the decrease of TEM specimen thickness. For magnetic devices, we directly observed the field distribution of a magnetic head in perpendicular magnetic recording, under different magnetic motivate forces. In the report, the observation results of nanocomposite rare-earth permanent magnetic materials, chemically synthesized magnetic nanoparticles will be introduced.

报告人简介:

夏卫星，2004年日本东北大学获博士学位，博士期间从事垂直磁记录薄膜及垂直磁记录系统的研究工作。2005-2009年在日本东北大学做博士后，从事透射电子显微镜方面的研究，利用电子全息技术和洛伦兹电镜方法做磁性材料的微观磁结构分析。2010年至2011年在日本理化学研究所外村彰教授研究组继续从事电子全息技术的开发和应用工作，以及电子显微镜的安装、部件设计和改造的工作。2011年加入中科院宁波材料所，入选中科院“高级技术支撑人才计划”，受聘为研究员，从事洛伦兹电镜设备建设和磁性材料的研究工作。近几年在NanoLetters、Nanoscale、J. Electron Microsc.等杂志发表SCI 学术论文30余篇。