Characterization of magnetic domain walls using electron magnetic chiral dichroism

Abstract

Domain walls and spin states of permalloy were investigated by electron magnetic chiral dichroism (EMCD) technique in Lorentz imaging mode using a JEM-2100F transmission electron microscope. EMCD signals from both Fe and Ni L_3,2 edges were detected from the Bloch lines but not from the adjacent main wall. The magnetic polarity orientation of the circular Bloch line is opposite to that of the cross Bloch line. The orientations of Fe and Ni spins are parallel rather than antiparallel, both at the cross Bloch line and circular Bloch line.     

微马达转子电镀导磁层的研究

本文推荐一种镀液，用于制作电磁型微电机转子坡莫合金导磁层，研究了该镀液的组成和工作条件对镀层成份和内应力的影响，表明该镀液具有可供选用的电流密度范围宽，允许较高Ｆｅ２－浓度和镀层内应力低等优点。     

Observation of Magnetic Domain Structures of Magnetic Thin Films by the Lorentz Electron Microscopy

Inthisdecade,agreatmanyresearchworksonmulti-layeredmopeticthinfilmshavebeenreport6d,sincethemagneticmulti-layeredfilmsarethemosthopefulnovelmagneticmaterialsforthenextgenerationelectionicdevises,suchasgialmagneto-resiSbocesensorelemeds.hiordertOdevel...     

A novel magnetic random access memory design using square ring elements for the hard layer

The behavior of narrow permalloy square rings under the influence of a magnetic field was studied using magnetic force microscopy (MFM). Two stable states of opposite polarity at remanence and simple switching were observed. We propose a design for the hard layer of magnetic random access memory (MRAM) that uses these states in square rings for data storage.     

Annealing behavior of electroplated permalloy thin films. II

The isochronal and isothermal annealing behavior of electroplated Ni-Fe thin films in the temperature range 373°–773°K has been investigated through measurements of electrical resistivity, coercivity, and relative permeability. Analysis of the experimental data indicates that the resistivity decrease is characterized by an activation energy of about 0.70 eV for temperatures up to 550 ° K, and by an activation energy of about 1.82 eV above this temperature. The coercivity initially decreases with an activation energy of about 0.71 eV, and then increases with activation energies up to 1.81 eV. The relative permeability decreases with an activation energy of 1.01 eV. The significance of these activation energies is discussed in terms of structural changes, and the results are compared with the annealing behavior of vapor deposited Ni-Fe thin films.     

基于MEMS工艺的高能量密度微电磁驱动器

提出了制作高能量密度电磁驱动器的工艺方法。利用微机械(MEMS)工艺在硅片上得到多匝平面线圈和磁芯的掩模图形,接着沉积种子层铜(Cu),然后对种子层进行整体Cu的电铸;当种子层生长到20 μm左右时,剥离硅片表面的镀层并用光刻胶保护磁芯位置的镀层;再用沿线电铸的方法对线圈进行电铸;最后保护制作好的线圈镀层,电铸NiFe合金材料。在10 mm×10 mm×0.38 mm的硅片上,制作出线圈匝数22×2(铜线截面积60 μm×60 μm、总长度达1 164 mm)、NiFe合金磁芯尺寸为3 mm×3 mm×0.2 mm的高能量密度微型电磁驱动器。把这种微型驱动器应用于无阀微泵做驱动实验:通入0.3 A的正弦电流时,微驱动器产生约50 mN的电磁力。实验结果表明:这种型微电磁驱动器在相同的输入功率下,比同类其他微电磁驱动器具有更高的能量密度,能产生更大的电磁驱动力。     

用坡莫合金作个人剂量仪的屏蔽材料

研究了用坡莫合金屏蔽层消除逆变电焊机等电器对核电站环境中使用的个人辐射剂量仪干扰的方法。提出了研究如电焊弧光之类干扰源的影响及防护的问题。对个人辐射剂量仪的抗干扰要求、相关标准的规定是否足够严密,提出了疑问。     

近十年来大功率磁性技术软磁材举发展的回顾与分析（一）

评述了大功率磁性技术中软磁材料的近十年发展史,所介绍的材料包括：硅钢、坡莫合金、软磁铁氧体、非晶和纳米晶合金、软磁复合材料等,并且分析了发展中的一些问题。     

碳包覆坡莫合金纳米粒子磁流体制备及表征

用热解(pyrogenation)-退火(anneal)法制备了碳包覆坡莫合金纳米粒子(carbon encapsulated permalloynanoparticles,CEPNPs),选用油酸为表面活性剂,煤油为载液,采用机械球磨法制备出CEPNPs磁流体.用XRD,粒度分析仪和HRTEM分析了CEPNPs的物相组成、粒度分布和微观形貌;用磁天平法测定了CEPNPs磁流体的磁性能;用旋转粘度仪探讨了其流变学性能.结果表明:制备的CEPNPs具有壳/内核包覆结构,平均粒径在75nm左右;以其制备的磁流体外观呈黑色粘稠状,稳定性好,在无磁场条件下磁流体粘度随转子转速的增大而减小,有外磁场时,磁流体粘度随磁场强度增大而增大.