利用玻莫合金磁阻传感器测量弱磁场

介绍一种新型玻莫合金磁阻传感器，利用玻莫合金磁阻传感器测量弱电流下的亥姆霍兹线圈磁场分布和验证毕奥萨瓦定理。     

新型各向异性磁阻传感器在地磁场测量中的应用

地磁场非常微弱,约为10-5T量级,测量难度大、精确度低.本文探讨了新型坡莫合金各向异性磁阻传感器在地磁场测量上的应用,实验发现新型磁阻传感器在地磁场等极微弱磁场测量中具有操作简单,灵敏度高,精确性好等优点.实验除具有实际应用价值外,同时适合在高等学校大学物理基础实验中开设出相应的实验教学内容.     

基于新型磁阻传感器的地磁倾角测量

地磁场非常微弱,约为10 5 T量级,这使得地磁倾角测量难度大、测量精度低.本文探讨了新型坡莫合金各向异性磁阻传感器在地磁倾角测量上的应用,实验发现新型磁阻传感器在地磁倾角测量中相比于其他方法具有操作简单,灵敏度高,精确性好等显著优点。实验除具有实际应用价值外,同时适合在高等学校大学物理实验中开设出相应的实验教学内容。     

NiFeNb种子层对坡莫合金磁滞回线的影响

以NiFeNb为种子层，制备(Ni₇₉Fe₂₁)_1-xNb_{x(5nm)/(Ni79Fe21) (20nm)/Ta(3nm)系列膜，并对其颗粒大小、 磁滞回线及表面粗糙度等进行测量，探讨种子层中Nb含量x对坡莫合金磁滞回线的影响.结果 表明，以NiFeNb作种子层能更好地改善坡莫合金的微结构. Nb含量为23％时的磁滞回线有最 小的最大磁能积、矫顽力.种子层影响坡莫合金磁滞回线的一个重要原因是脱附激活能等因 素造成种子层具有不同的表面粗糙度，进而使坡莫合金具有不同的微结构和磁性能. 关键词： NiFeNb种子层 坡莫合金 磁滞回线 粗糙度}     

某型无人机系统雷电脉冲磁场效应

为检验雷电脉冲磁场辐射环境下无人机系统的安全可靠性,以某型无人机为试验对象,利用亥姆霍兹线圈和雷电浪涌发生器模拟雷电脉冲磁场,开展了无人机雷电脉冲磁场效应试验。实验结果表明,GB50057-94推荐的8/20μs雷电脉冲磁场不会干扰无人机通信而导致数据链失锁,但是机载三轴磁航向传感器受磁场干扰严重,产生零点漂移并造成已知方向上读数偏差,且放电极性决定航向角变化趋势。经过机理分析发现,在线性工作区间内磁航向传感器能够利用各向异性磁阻效应引起电阻阻值变化的规律正常工作,但高峰值雷电脉冲磁场会导致坡莫合金电阻内部磁畴排列紊乱而出现磁化,改变了传感器磁敏感度以及输出特性,且只出现在磁敏感方向上。     

巨磁电阻效应实验仪的研制与应用

阐述了巨磁电阻效应实验原理、实验内容和实验方法,该仪器可测量巨磁电阻阻值与磁感应强度关系,并与正常磁电阻、坡莫合金磁电阻特性进行比较,仪器还提供巨磁电阻传感器特性测量及系列应用实验供教学使用.     

Ni—Fe—Nb及Ni—Fe—Nb—Al合金磁性和结构的初步研究

对两类合金,即Ni-Fe-Nb和Ni-Fe-Nb-Al合金的热处理和磁性进行了实验。Ni-Fe-Nb合金经高温处理后与工业常用的钼坡莫合金同样具有较高的起始磁导率和最大磁导率。我们对Ni-Fe-Nb和4钼坡莫合金的物理参数进行了比较。Ni-Fe-Nb-Al合金有较高的硬度和电阻率。经过两次联合处理,可以达到较为适用的磁导率值。Ni-Fe-Nb-Al合金经高温缓慢冷却发生了调幅结构,调幅结构的周期约50单胞(数)或160埃。Ni-Fe-Nb-Al合金经970℃加热后快速冷却可以抑制调幅结构。具有调幅结构的材料硬度较高,矫顽力也略为增高。 关键词：     

磁阻传感器测量地磁场实验教学体会

简要介绍了磁阻传感器的结构和工作原理,解释了标定磁场在地磁场测量中的作用。在此基础上,进一步分析了在不同磁场下磁阻传感器管脚如何调整方向以及在地磁场测量中如何找到地磁子午面等问题,通过具体的操作使学生对磁阻传感器测量地磁场实验的理解能够更加深入。     

巨磁电阻效应实验仪

自制了巨磁电阻效应实验仪,测量了不同外磁场和工作电压下巨磁阻传感器输出电压的变化.研究了巨磁阻传感器敏感轴与外磁场间夹角与传感器输出电压间关系,传感器输出电压的与偏离角度成余弦关系.     

GdHO_（0．15）合金电阻率研究

本文利用纯Ｇｄ掺ＨＯ构成ＧｄＨＯ０１５合金，研究居里温度变化．居里温度由纯Ｇｄ的Ｔｃ＝２９３Ｋ，变化到ＧｄＨＯ．１５合金的Ｔｃ＝２７８Ｋ．并在１．５Ｔ外磁场下，液氮温区，研究磁阻变化规律．结果纯Ｇｄ的磁阻在此范围内为负的，而掺ＨＯ后，ＧｄＨＯ０．１５合金的磁阻力正，证明了掺杂ＨＯ原子影响了Ｇｄ的自旋涨落．     

Peculiarities of permalloy thin film microcore hysteretic magnetization process in high space resolution fluxgate device

Magnetization processes of the sectioned thin film permalloy core were examined in relation with its geometrical dimensions using magnetooptical Kerr technique and ferrofluid observation. It is shown quantitatively the intermediate case between Stoner–Wohlfarth and zero internal field contradicting models takes place. Ferrofluid investigation had shown the stable quasi-saturated state with closing domain structures at permalloy bar edges. Magnetization reversal occurs by hysteretic manner but the hysteresis loop parameters are reproducible and depend strongly upon core geometry. Hysteresis is characterized by parallelogram form with clear critical field and loop slope depending on bars dimensions and their mutual position in array. Loop shape approaches the rectangular form and critical field increases if bar thickness t, width w and bar density in array are decreased. The critical field value H_cr is defined by demagnetizing field at bar edges while the saturation field H_s depends only on width w at of a bar in array. Variation of the bar form or shift of every second bar in array possesses to increase the core thickness to enhance the stray field without increase of the saturating exciting current. The core described can be used with magnetooptical garnet film or Hall sensor in fluxgate regime for magnetic field measurement with space resolution 10–100 mcm.     

Magnetoresistive Fe19Ni81/Tb-Co medium with an internal magnetic bias

The magnetization reversal and magnetoresistance of two-layer exchange-coupled Fe19Ni81/Tb-Co films are studied. Amorphous Tb _x Co_{100 − x} layers with 30 < x < 35 are found to have a uniaxial magnetic anisotropy and a rather high coercive force, which ensures magnetic biasing of the adjacent permalloy layers. In addition, the permalloy layers subjected to selective annealing exhibit a significant anisotropic magnetoresistance and a small magnetic hysteresis. These properties make it possible to consider the developed film structure as an effective magnetoresistive medium. This structure is used to form magnetic sensor samples that have an odd transfer function in the absence of external magnetic biasing.     

Dynamic response of permalloy/Cu/Co magnetoresistive sandwiches

The dynamic response of trilayer magnetoresistive permalloy/Cu/Co films was studied by high-frequency permeability spectra measurements. The resonance frequency is shown to depend on the interlayer copper thickness. This dependence is related to exchange coupling between permalloy and cobalt and the interaction field is estimated using the Landau–Lifschitz–Gilbert model.     

RF-photon induced Mössbauer satellites in permalloy

The Mössbauer spectra of a permalloy film placed in an rf magnetic field are measured. The film is so thin that transverse magnetostriction oscillations are not excited in it. This permits the observation of satellites that are due solely to periodic variations of the magnetic field at the nucleus. The data are in good agreement with calculations performed in the model of step-wise field reversals. On application of an additional static magnetic field the splitting of the satellites is observed, as predicted by the model of asymmetric step-wise field reversals.     

Nanoscale zeeman localization of charge carriers in diluted magnetic semiconductor-permalloy hybrids

We investigate the possibility of charge carrier localization in magnetic semiconductors due to the presence of a highly inhomogeneous external magnetic field. As an example, we study in detail the properties of a magnetic semiconductor-permalloy disk hybrid system. We find that the giant Zeeman response of the magnetic semiconductor in conjunction with the highly nonuniform magnetic field created by the vortex state of a permalloy disk can lead to Zeeman localized states at the interface of the two materials. These trapped states are chiral, with chirality controlled by the orientation of the core magnetization of the permalloy disk. We calculate the energy spectrum and the eigenstates of these Zeeman localized states, and discuss their experimental signatures in spectroscopic probes.     

Effect of etching on the electrical and magnetic properties of writer shield material

Magnetron sputtered permalloy films are treated by wet chemical etchings with acid etchant as well as fluorine based reactive ion etch (RIE). Upon these treatments, the resistivity and coercivity of the permalloy film increase is within 10 %. No significant increase observed with prolonged etching time. The effective magnetization change of the permalloy films are within 5 % post the treatments. Atomic force microscope (AFM) and transmission electron microscope (TEM) are used to study the surface and interface evolution of permalloy film upon etching. The small impact on the electrical and magnetic properties of permalloy films can be correlated with the surface oxide protecting layer formation during the etch. Consequently, sputtered NiFe is a safe material to expose to these etching processes for write pole shield application.     

Magnetic shielding for DAMPE electromagnetic calorimeter PMTs

The magnetic characteristics of R5610A-01 photomultiplier tubes are studied in this paper. The experimental data shows that the gain of R5610A-01 loses about 53% when the magnetic field is 3 Gs along its +X axis. A cylinder of one-layer permalloy strip is able to reduce the effect of a 3 Gs magnetic field on the PMT gain to less than 1%.     

Video-rate electron-holographic interference microscopy using a liquid-crystal panel

This paper describes interference microscopy using a liquid-crystal panel as a rewritable medium. This system makes it possible to observe the dynamic behavior of a magnetic field. Experimental results obtained while observing dynamic domain-wall motion in a thin permalloy film are shown.