Study on mesoscopic physical phenomenon in many particle systems by electron holography

电子全息研究多粒子系统介观物理现象

• 批准号: 11650671
• 负责人: KONNO Toyohiko
• 金额: $ 2.24万
• 依托单位: Tohoku University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11650671/
• 关键词: Transmission electron microscopy; Electron holography; Clusters; Cluster assemblies; Magnetic properties; Tunneling conductivity; Mesoscopic system; 磁性クラスター

We employed Hitach HF-2000 transmission electron microscopy for electron holography experiments. The biprism wire was installed between the two intermediate lenses of the microscope, and several ten to 100 voltages was applied to the wire. Having confirmed the reproducibility of the interference fringes, we first used latex particles of approximately 1μm in diameter as a specimen. Reconstructed phase images exhibited equipotential curves around the particles, which was interpreted to represent the electrostatic field around the particles. Next, we observed Nd-Fe-B alloy powders with the same technique. From the reconstructed phase image, it was concluded that a magnetic flux of approximately 4.1x10^<-14> Wb penetrated into the about 1μm area of the tip of the specimen.In addition, we synthesized monodispersive Co/CoO cluster assembly using plasma gas condensation (PGC) technique. This cluster assembly exhibited strong uniaxial magnetic anisotropy. The detailed observation on the magnetic relaxation behavior indicated macroscopic quantum tunneling effect is operating below 8K.In addition, CoAl intermetallic alloy clusters were generated by the PGC technique for the first time. By controlling processing conditions, it was possible to change both the composition and size of the clusters. The Co-rich alloy clusters clearly exhibited ferromagnetic behavior.

我们使用Hitach HF-2000透射电子显微镜进行电子全息实验。将双棱镜线安装在显微镜的两个中间透镜之间，并向该线施加数十至100个电压。在确认了干涉条纹的再现性之后，我们首先使用直径约为1μm的乳胶颗粒作为样品。重构的相位图像显示出粒子周围的等势曲线，这被解释为代表粒子周围的静电场。接下来，我们用同样的技术观察Nd-Fe-B合金粉末。从重建的相位图可以看出，<-14>在样品尖端约1μm的区域内，有约4.1 × 10 ~（-1）Wb的磁通穿过。这种团簇组装表现出很强的单轴磁各向异性。对磁弛豫行为的详细观察表明，在8 K以下存在宏观量子隧穿效应。此外，首次利用PGC技术制备了CoAl金属间化合物团簇。通过控制处理条件，可以改变团簇的组成和大小。富Co合金团簇明显表现出铁磁行为。

项目成果

T.J.Konno: "Structure and Magnetic Properties of Cosputtered CoC Thin Films"J.Magn.Magn.Maler.. 195. 9-18 (1999)

T.J.Konno：“共溅射 CoC 薄膜的结构和磁性”J.Magn.Magn.Maler.. 195. 9-18 (1999)

D.L.Peng, K.Sumiyama, T.Hihara, S.Yamamuro and T.J.Konno: "Magnetic properties of monodispersed Co/CoO Clusters."Phys.Rev.B. 61. 3103-3109 (2000)

D.L.Peng、K.Sumiyama、T.Hihara、S.Yamamuro 和 T.J.Konno：“单分散 Co/CoO 簇的磁性。”Phys.Rev.B。

T.J.Konno: "Guinier-Preston (GP) zone revisited : atomic level observation by haadf-tem technique"Scripta Materialia. 44(in press.). (2001)

T.J.Konno：“重温 Guinier-Preston (GP) 区域：通过 haadf-tem 技术进行原子级观察”Scripta Materialia。

D.L.Peng: "Characteristic Tunnel-Type Conductivity and Magnetoresistance in a CoO-coated Monodispersive Co Cluster Assembly"Applied Physics Letters. 74. 76-78 (1999)

D.L.Peng：“CoO 涂层单分散 Co 团簇组件中的特征隧道型电导率和磁阻”应用物理快报。

N.Nomura: "Fracture toughness improvement of TiC by Nb and Mo precipitates."J.Mater.Scr.Lett.. 19. 1879-1881 (2000)

N.Nomura：“通过 Nb 和 Mo 沉淀物提高 TiC 的断裂韧性。”J.Mater.Scr.Lett.. 19. 1879-1881 (2000)