一种新的自旋量子效应——电流感应磁化翻转

电流感应的磁化翻转效应是近年来继巨磁阻效应(GMR)和隧道磁阻效应(TMR)之后提出的一种nm尺度下新的自旋相关效应,在无外加磁场的情况下,垂直于铁磁层平面的自旋极化电流就能引起铁磁层的磁化翻转。该效应有望被用于制作新型的电流操纵磁存储器件。报道了该效应的理论和实验的研究进展。     

对砝码磁性测量的研究

砝码磁性是递过磁化率和永久极化强度来描述。随着电子天平和高精度电子比较的仪的普及,砝码磁性对砝码检定的影响越来越明显。文章通过磁化率计法测摄砝码磁化率和永久极化强度的研究,提出了使用划分非正圆柱体砝码检定磁化率的实现方法,以指导我们的日常检定工作。     

磁化处理对水中藻类的去除效果研究

采用强磁场对藻类含量高的水体进行磁化处理,探讨了磁化处理过程中水样流速、循环时间、藻类初始浓度对磁化处理效果的影响。研究发现磁化处理对藻类的去除有明显的效果,通过对各个影响因素的研究表明在水样流速为3．78m/s,循环时间为360min时,藻类的去除效果比较好。     

一种新型油田堵水剂的制备

以自制Fe3O4磁粉、微晶纤维素与淀粉、丙烯酸,交联剂为主要原料合成了磁性高吸水性树脂。探讨了Fe3+、Fe2+加入速度对Fe3O4磁粉的影响以及Fe3O4磁粉加入对磁性高吸水性树脂的饱和磁化强度、吸水率的影响。结果表明,Fe3+、Fe2+加入速度过快,Fe3O4磁粉磁性降低。实验测得磁性高分子吸水树脂的饱和磁化强度为0.7 Am2/kg、吸水率为60 g/g,能够应用于油田堵水领域中。     

二灰稳定磁化轮道路基层在迁安市的推广应用

通过对二灰稳定磁化轮和二灰稳定碎石配合比设计中强度的比较以及用二灰稳定磁化轮做道路基层的试验,分析了二灰稳定磁化轮道路基层的经济效益和社会效益,阐述了磁化轮在工程建设中广阔的应用前景。     

饱和铁心型超导限流器满足电网重合闸条件分析

饱和铁心型超导限流器(saturated iron-coresuperconducting fault current limiter,SI-SFCL)在限流过程中独特的非线性阻抗变化特性与电网继电保护的配合是一项关键技术,尤其是限流器在完成限流后需要快速恢复,以配合电网断路器重合闸的要求。限流器的恢复过程本质上是超导磁体的重新励磁,既要在尽量短的时间内完成超导磁体的充磁,又要尽量降低快速励磁时对励磁电压、电流的要求,降低直流励磁系统的设计难度,并提高设备运行的安全性和稳定性。基于对上述超导限流器重合闸要素的分析,得出结论:SI-SFCL在电网重合闸时,直流励磁不必完全恢复至额定工作值,只要能够确保在一定交流退磁作用下,铁心的最小磁化强度处于磁化曲线的拐点处即可。用PSIM进行仿真分析,校验了该判据的合理性。     

纳米磁性Mn3O4粉末的溶剂热法合成及表征

以MnO2为主要原料,应用溶剂热法合成了纳米磁性Mn3O4粉体.研究和讨论了反应温度、填充度、溶剂种类、降温速率对产物性能的影响,得到溶剂热法制备纳米磁性Mn3O4的最佳条件.产物经XRD表征为单一相Mn3O4,经粒度分析仪及透射电镜(TEM)检测,为四方晶型,平均粒径为55nm.     

Magnetic Properties of Al-Doped Na0.7Co1-xAlxO2

Single phase polycrystalline samples Na0.7Co1-xAlxO2 (x=0, 0.05, 0.10, 0.15, 0.20, 0.25, 0.30) were prepared by solid state reaction. The magnetic properties from 5 K to 300 K have been studied by dc and ac magnetic susceptibility measurements. Samples with lower doping quantity (x=0, 0.05, 0.10) showed paramagnetic behaviors, but those with higher doping quantity (x=0.20, 0.25, 0.30) showed spin-glass behaviors with a freezing temperature (Tf) of about 13 K.     

Review on recent advances of zinc substituted cobalt ferrite nanoparticles: Synthesis characterization and diverse applications

Researchers have taken a prodigious consideration in characterizing and synthesizing zinc substituted cobalt ferrite nanoparticles because of their substantial applications across diverse technological and industrial fields. Zinc substituted cobalt ferrite nanoparticles are a class of lenient magnetic nanomaterials, which have potentially high magnetic, optical, electrical, and dielectric properties. These properties include a high value of permeability, low power losses, permittivity, saturation magnetization, coercivity, resistivity, and other beneficial properties that make them promise candidates for applications in various fields. These ferrites are also used in biomedical areas such as MRI and cancer treatments. In electronic fields, zinc substituted cobalt ferrite nanoparticles are used to make transducers, transformers, biosensors, and sensors. Apart from these advantages, they are found in our everyday electronic and electrical appliances like LED bulb, refrigerator, mobile charger, TV, microwave oven, juicer, washing machine, mixer, iron, printer, laptop, mobile, desktop, etc. Hence, the current review reports some properties of these spinel ferrites and emphasizes the different synthesis techniques that can be used to prepare them. Afterward, the impact of dopant on the materials' properties, the characterization techniques, and the momentous application in the present era have been well discussed.     

Negative magnetization and exchange bias effect in Fe-doped CoCr2O4

Polycrystalline ceramics of Co(Cr_1-xFe_x)₂O₄ (0?≤?x?≤?0.12) were experimentally studied based on a series of temperature and time-dependent dc magnetic measurements using different magnetic field histories. Magnetization in field cooling process was continuously decreased for doping content x in the range of 0?≤?x?≤?0.04. Remarkable negative magnetization is observed when x reaches to 0.06 and persists up to x?=?0.1. Two-sublattice model is established and competition of the two magnetic sublattices is responsible for the phenomenon. The magnetic switching effect is realized just by changing the magnitude of the applied magnetic field and double magnetocaloric effects are obtained. These unique features under low magnetic fields show attractive for application in spintronic devices due to that the magnetic state can effectively be tuned through magnetic field or temperature. Besides, the system exhibits both positive and negative exchange bias fields which are considered to be originating from the unidirectional anisotropy of exchange coupling of antiferromagnetic/ferromagnetic phases and spin reorientation of the two sublattices magnetic moments, respectively.