磁场强度波形畸变对交流磁滞回线形状的影响

测量了软磁铁氧体环形样品在不同条件下的交流磁滞回线,发现磁滞回线形状随交流磁场强度H的幅值、频率而变化.交流磁滞回线形状的变化是由于磁场强度H波形畸变造成的,在弱交变场下,当磁感应强度B作正弦变化时,磁场强度H也作正弦变化,此时磁滞回线形状为椭圆;当磁场增强时,H-t曲线发生了不同程度畸变,且磁场强度越强,H-t曲线畸变程度越严重,此时磁滞回线变弯变尖,呈胖S形.通过理论分析及实验拟合对磁滞回线形状变化做出了解释.     

铁磁材料交流磁化曲线及磁滞回线的观测

分析了磁化曲线和磁滞回线的各个参量及变化规律,论述了如何选择电路参量,并给出了测量电路,推导了样品中的磁感应强度.最后分析了实验中要注意的几个主要问题,如:不同几何形状铁磁材料的磁化曲线及磁滞回线的测量,不同成份铁磁材料的磁化曲线和磁滞回线的特征及其应用,励磁电源、励磁和探测电路参量对磁滞回线的影响以及居里温度的测定等.     

基于NI数据采集器的动态磁滞回线测量

通过搭建磁滞回线测试系统,结合数据采集卡和Labview软件实现磁滞回线的自动测绘和保存,丰富了实验内容,培养了学生的实际动手能力。     

采用BP神经网络拟合铁磁材料的磁滞回线

介绍了采用BP神经网络模拟人脑智能拟合铁磁材料磁滞回线的方法,给出了实现磁滞回线拟合的BP神经网络结构模型.拟合结果表明,该方法拟合精度较高,对解决非线性拟合问题非常有效.     

用运算积分器替代RC电路测铁磁材料的动态磁特性

示波器法测定软磁样品的动态磁滞回线,实验常用图1电路,螺绕环次级为RC积分电路.磁滞回线顶点(Hm,Bm}的计算公式为实验内容为:1.逐次增加电位器W的输出电压,使磁滞回线由小至大,把逐次的     

Mathematic软件在铁磁材料磁滞回线中的应用

根据铁磁材料磁滞回线的实验原理,利用绘图软件Mathematic绘制出样品的磁化曲线和磁滞回线,对实验数据进行多项式函数拟合,计算出其磁滞损耗。     

基于Matllab的约束最小二乘法拟合磁滞回线

由实验测得的磁滞回线数据的是一系列离散、带噪声的值。通过约束最小二乘方法对曲线进行分段拟合,使曲线的畸变程度得到了改善,准确地表达磁滞回线的特性,为磁材料的定量分析述提供了基础。     

铁磁材料动态磁滞回线测绘方法的优化设计

文中介绍一种涉及铁磁材料动态磁滞回线测绘方法的优化设计.该设计能观察和测绘硬、软磁样品的动态磁滞回线,观察、测绘速度快,方法简便,检测有关数据较准确.     

磁滞回线测量仪的设计

为了测量多种形态磁性材料的磁滞回线,设计了磁滞回线测量仪.该仪器的磁感应强度探测器采用双线圈反相连接的方式,磁性材料可以放于任一探测线圈中,方便更换.测试表明,该套实验仪器具有良好的性能,输出图形清晰、分辨率高.     

不同易轴取向下对Nd_2Fe_(14)B/Fe_(65)Co_(35)磁性双层膜的微磁学模拟

运用三维数值模拟计算方法,计算了膜面外不同易轴取向下Nd2Fe14B/Fe65Co35磁性双层膜的磁滞回线、角度分布、成核场、矫顽力和磁能积等,并与实验结果进行了细致比较.计算结果表明:只有当易轴与外场之间的夹角β=0?时,才有明显的成核现象,其成核场和矫顽力均随着软磁相厚度Ls的增加而降低;随着易轴偏角β的增大,剩磁逐渐减小,磁滞回线的方形度降低,从而磁能积减小,在Ls=1 nm,β=0?时磁能积(561.61 kJ/m3)最大.理论计算所得的磁滞回线与实验磁滞回线符合得很好,剩磁和矫顽力的理论值与实验值相差很小.     

The permeability and remanent magnetization of a randomly inhomogeneous two-phase medium

A randomly inhomogeneous composite consisting of two, ferromagnetic and nonmagnetic (para-or diamagnetic), phases is considered. The dependence of the effective permeability of the composite on the concentration of the ferromagnetic phase and on the applied magnetic field is found for the case of the negligible hysteresis loop. When the hysteresis loop is appreciable, the remanent magnetization as a function of the ferromagnet concentration is calculated.     

Hysteresis behaviors in a cylindrical Ising nanowire

The hysteresis behaviors of the cylindrical Ising nanowire are investigated within the effective-field theory with correlations at temperatures below, around and above the critical temperature. The hysteresis curves are obtained for different reduced temperatures both ferromagnetic and antiferromagnetic interactions between the shell and the core. We find that the hysteresis loop areas decrease when the reduced temperatures increase, and the hysteresis loops disappear at certain reduced temperatures. Moreover, for the antiferromagnetic nanowire the hysteresis loop areas disappear earlier than the ferromagnetic case as the reduced temperature increases. An unusual form of triple hysteresis behaviors is observed for the antiferromagnetic nanowire system. The thermal behaviors of the coercivities and remanent magnetizations are also investigated. The results are in good agreement with some experimental and theoretical results.     

Anisotropic pinned/biased magnetization in SrRuO3/SrMnO3 superlattices

The exchange coupling at the interfaces of magnetic superlattices consisting of ferromagnetic SrRuO3 and antiferromagnetic SrMnO3 grown on (001) oriented SrTiO3 is studied with in-plane and out-of-plane orientations of the cooling magnetic field, with respect to the substrate plane. The magnetization of the in-plane, field cooled hysteresis loop is lower than the corresponding in-plane zero-field-cooled hysteresis loop. The out-of-plane field cooled hysteresis loop is shifted, from the origin, along the graphical magnetization axis. We attribute this irreversible rotation of the moment to the pinning/biasing of spin in the SrRuO3 layer in the vicinity of interfaces by the antiferromagnetic SrMnO3 layer.     

外场作用下铁电/铁磁双层膜的极化磁化性质

建立了铁电/铁磁双层膜模型,铁电层的电矩用连续标量描述,而铁磁层的自旋应用经典矢量描述.利用蒙特卡罗方法模拟了体系的热力学性质和极化、磁化行为.给出了零场下体系的内能、比热、极化和磁化随温度变化的关系,并分别研究了体系在外磁场和外电场下的极化和磁化行为.模拟结果表明,双层膜体系的内能、比热、极化和磁化性质因层间耦合系数的不同而明显不同,当界面耦合较弱时,双层膜表现出各自的热力学性质,当层间耦合增强到一定程度时,双层膜耦合为一个整体,表现出统一的热力学性质.该双层膜在外场中形成电滞回线和磁滞回线,并表现出偏置特性,界面耦合强度和温度影响滞后回线和偏置现象.     

椭圆交流磁滞回线和交流磁参量的测定

用霍尔元件做探头,用示波器测量和研究了铁磁材料的椭圆交流磁滞回线的性质和参量。     

Magnetic and ferroelectric properties of Zn and Mn co-doped BaTiO_3

This paper reports an approach to obtaining multiferroic properties in co-doped(Zn:Mn) Ba Ti O3 near room temperature.Interestingly,an unusual magnetic hysteresis loop is observed in the co-doped compositions in which the central portion of the loop is squeezed.However,in the composition Ba0.9Zn0.1Ti0.9Mn0.1O3,a broad magnetic hysteresis loop is observed.Such a magnetic effect is attributed to the coexistence of antiferromagnetic and ferromagnetic exchange interactions in the system.The observation of the above type of magnetic properties is likely to be due to the presence of exchange interactions between Mn ions.A lossy-type of ferroelectric hysteresis loop is also observed in co-doped ceramic compositions near room temperature.     

Terfenol-D/PZT磁电复合材料的磁电相位移动研究

采用粘合法制备了叠层结构的块体Terfenol-D/PZT磁电复合材料,测量了不同频率下的磁电回线,采用新的极坐标下的方式做图.从极坐标下的磁电回线中可以看出,随直流磁场的变化,非谐振频率下的磁电相位发生了轻微移动,移动幅度随频率的增加而增加;而在谐振频率下,伴随着巨磁电效应,磁电相位发生了显著移动,移动幅度达到了近90°.与粉末Terfenol-D/环氧树脂/PZT磁电复合材料对比之后表明,非谐振频率下块体Terfenol-D/PZT的磁电相位移动主要由涡流引起;而谐振频率下大幅度相位移动则主要来源于Terfenol-D的磁致弹性变化.     

Deterministic and non-deterministic switching in chains of magnetic hysterons

This paper presents a fundamental analysis of a single-domain ferromagnetic particles chain hysteresis in perpendicular geometry as a prototype for ultra-high density memories. Due to magnetostatic long range interactions the system has a complex hysteresis but stable features can be found. The loop has a number of deterministic Barkhausen jumps and consequently a number of stable plateaus that could be used in multistate memories. The fundamental elements that sustain this behavior are shown and discussed.