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.     

多层膜巨磁电阻特性及电流最佳测量

测量了不同方向外磁场和温度下多层膜巨磁电阻的磁阻特性,给出了巨磁电阻模拟传感器用于电流测量的最佳磁偏置.结果表明:外磁场强度相同但方向不同,对巨磁电阻的作用效果不同,巨磁电阻饱和时,阻值与外磁场方向无关.温度不同,巨磁电阻的阻值不同,磁电阻变化率也有改变.     

巨磁电阻效应及应用设计性物理实验的研究

测量巨磁电阻阻值与磁感应强度的关系,研究巨磁电阻效应特性,介绍巨磁电阻效应的物理原理、实验方法及应用,该近代物理学的研究成果,可作为大学物理实验教学内容.     

(CoFe)_(1-x)Ag_x颗粒巨磁电阻薄膜的磁折射效应研究

在线非接触测试巨磁电阻效应对磁电子器件的工业化生产具有重要的意义 .用红外光谱研究了 (CoFe) 1 -xAgx颗粒薄膜的磁折射效应 ,研究表明在红外波段 ,一级近似可以认为巨磁电阻比值与磁折射变化率成正比 ,可以利用磁折射效应作为在线非接触工具测量与自旋散射相关的巨磁电阻效应 .     

磁电子学讲座 第六讲 巨磁电阻效应在信息存储等领域中的应用

用巨磁电阻材料构成磁电子学新器件，已开始在信息存储领域成功地获得了应用．文章介绍了用于计算机硬磁盘驱动器的巨磁电阻磁头和巨磁电阻随机存储器，描述了它的工作原理、性能特点及发展趋势．指出巨磁电阻材料在传感器方面的应用也令人瞩目，有着广阔的市场前景．     

第六讲 巨磁电阻效应在信息存储等领域中的应用

用巨磁电阻材料构成磁电子学新器件，已开始在信息存储领域成功地获得了应用，文章介绍了用于计算机硬磁盘驱动器巨磁电阻磁头和巨磁电阻随机存储器，描述了它的工作原理，性能特点及发展趋势，指出巨磁电阻材料在传感器方面的应用也令人瞩目，有着广阔的市场前景。     

磁电子学器件应用原理

本文介绍几种重要的磁电子器件的基本结构和工作原理,包括巨磁电阻与隧穿磁电阻传感器、巨磁电阻隔离器、巨磁电阻与隧穿磁电阻硬盘读出磁头、磁电阻随机存取存储器、自旋转移磁化反转与微波振荡器。自旋晶体管作为未来磁电子学或自旋电子学时代的基本元素,目前大都还处在概念型阶段,本文也将对几种自旋晶体管的大致原理作简要介绍。     

磁电子学器件应用原理

本文介绍几种重要的磁电子器件的基本结构和工作原理,包括巨磁电阻与隧穿磁电阻传感器、巨磁电阻隔离器、巨磁电阻与隧穿磁电阻硬盘读出磁头、磁电阻随机存取存储器、自旋转移磁化反转与微波振荡器。自旋晶体管作为未来磁电子学或自旋电子学时代的基本元素,目前大都还处在概念型阶段,本文也将对几种自旋晶体管的大致原理作简要介绍。     

自旋阀与多层膜巨磁电阻的特性测量及比较

介绍磁性多层膜中自旋极化输运和巨磁电阻效应,简述自旋阀巨磁电阻与多层膜巨磁电阻在材料组成结构和工作原理方面的区别,利用和改造现有的高校物理实验室中的实验仪器并设计简易的实验电路测量这两种类型的巨磁电阻的磁敏特性,并根据实验测量的结果将这两种传感器在其灵敏度和测量范围上进行比较和研究.     

基于巨磁电阻效应的多功能测量仪

利用巨磁电阻传感器设计了多功能测量仪器,实验表明该测量仪能够精确测量物体的转速和转角,直观地演示行驶车辆对地磁场的扰动.     

Measurement of nonlinear refractive index of Ag and Au nano-particles using moiré technique

In this paper we have measured second order nonlinear refractive index of Ag and Au nano-particles using the moiré deflectometry with a CW He-Ne laser at wavelength of 632.8 nm. The main advantages of this technique are its extreme experimental simplicity and low sensitivity to external distribution in comparison with other interfrometric methods that need very stable experimental set-up. Because of self-focusing (or self-defocusing) that is due to intensity dependent refractive index, presence of sample in the moiré deflectometry set-up lead to rotation of moiré fringes. By moving the sample in set-up we have measured these rotation angles in different displacements from focus point of lens used in this set-up and then we have calculated the nonlinear refractive index of Ag and Au nano-particles using their values. Also we have obtained the sign of n₂ regard to the direction of rotations. Consequently by using the Mathematica software we have exhibited the suitable fitness of theoretical curve with experimental results.     

Application of magneto-optical method for real-time visualization of eddy currents with high spatial resolution for nondestructive testing

In this paper we describe a new, laser supported, eddy current microscope for the real-time visualization of eddy current distributions. In the experimental set-up, the induction of eddy currents is conventionally performed by an alternating current excitation coil above the object surface. The magnetic field induced by the eddy currents is detected by the use of the Faraday effect. For that purpose, a laser beam is passed through a suitable thin crystal integrated in the excitation coil. The polarization direction of the laser beam is rotated in this thin crystal depending on the local magnetic field. The area distribution of the rotation angle is transformed into a grey value picture using an optical set-up, which comprises a conventional microscope, a lighting technique, an analyzator, and a CCD sensor. By choosing a suitable optic, a real-time measurement of the magnetic field with a high spatial resolution can be carried out. In this paper, the basic physics and the design of the new microscope are described. The initial results of experimental investigations concerning the resolution power of magneto-optic eddy current sensors are presented and compared with conventional eddy current sensors.     

Magnetostrictive GMR sensor on flexible polyimide substrates

The feasibility of a stress sensor based on giant magneto-resistance (GMR) on a flexible polyimide substrate is presented. Therefore, a stack system with a GMR effect of up to 8.6%$8.6\%$ has been deposited on a polyimide substrate and patterned to micrometer scaled sensor elements. An in-plane tensile stress was applied to the sensor to achieve a rotation of the anisotropy of the magnetostrictive free layer. The magneto-optical and magneto-resistive effect was measured. The stress dependence of the Co₅₀Fe₅₀ free-layer magnetization was measured up to an elongation of 2.5% in a CoFe/Cu/CoFe spin valve. The magneto-optical results are compared to the resistance loops of the sample. Furthermore, the normalized sensor output is shown as a function of the applied stress at several bias fields and at the remanent state.     

Hysteresis modeling of synchronous reluctance motor considering PWM input voltage

This paper deals with the hysteresis characteristics analysis in PWM fed synchronous reluctance motor (SynRM) using a coupled finite element method (FEM) and Preisach's modeling, which is presented to analyze the characteristics under the effect of saturation and hysteresis loss. With regard to the PWM characteristics, a vector control inverter is combined with an analysis tool. Also, a moving mesh technique is used with regard to rotation due to velocity. The focus of this paper is the applied method of Preisach modeling for rotating machines and the characteristics analysis of a SynRM using the proposed method of analysis. For the propriety of proposed method of analysis, TMS320C31 DSP-installed experimental devices are used. And then, computer simulation and experimental result for the i–λ loci, speed, current response, show the propriety of the proposed method. The characteristic analysis is performed in relation to the maximum efficiency condition for a SynRM in simulation and experiment.     

巨磁电阻特性的研究及其在物理实验教学上的应用

阐述了巨磁电阻效应的机理,利用AA002系列巨磁电阻(GMR)器件测量了单个巨磁电阻的阻值与磁场磁感应强度的关系以及AA002系列巨磁电阻(GMR)器件的输出电压与外磁场的关系,研究了巨磁电阻效应的特性,并设计了巨磁电阻器件在物理实验教学中的实用性比较广泛的系列实验.     

A study of the velocity relations in the rail-accelerator without an external magnetic field

The experimental results of the measurement of the plasma cluster velocity in the rail-accelerator and their theoretical analysis are presented in this paper. The experimental set-up with simple pulse electromagnetic valve enabling to strike a discharge is described here. The dependences of the plasma cluster velocity on the voltags between electrodes and on different capacitances of the condenser battery are studied.     

Micromagnetic simulations on detection of magnetic labelled biomolecules using MR sensors

In this work, we present a study of the interaction between the magnetic particles used in biological applications and the giant magnetoresistive effect (GMR) sensor. The fractional change in resistance, and hence the sensitivity, will be maximized by matching, as far as possible, the size of the sensor to the size of the beads and by carefully positioning the beads over the sensor. We found, by micromagnetic simulations, that the amount of the surface coverage with magnetic particles may affect the magnetization curve of the sensor and will change the field dependence of the GMR response.     

方波电泳电场驱动下液膜马达的电致流动特征

液膜马达作为一种新颖的实验装置在基础研究和技术应用方面都将会发挥着重要的作用, 深入研究各种条件下液膜马达的电致流动特征是非常有意义的. 本文从理论上研究了均匀恒定外电场中的液膜马达在方波电泳电场驱动下的动力学特征, 解析地给出了液膜转动的线速度随时空变化的规律. 理论结果表明, 液膜会随着电泳电场频率的增大由对称性往复转动逐渐转变为振动, 这不仅有助于从理论上认识液膜马达振动的物理根源, 也为在实际应用中设计液膜搅拌机提供了一种新思路.     

Effect of kinesin velocity distribution on slow axonal transport

The goal of this paper is to investigate the effect that a distribution of kinesin motor velocities could have on cytoskeletal element (CE) concentration waves in slow axonal transport. Previous models of slow axonal transport based on the stop-and-go hypothesis (P. Jung, A. Brown, Modeling the slowing of neurofilament transport along the mouse sciatic nerve, Physical Biology 6 (2009) 046002) assumed that in the anterograde running state all CEs move with one and the same velocity as they are propelled by kinesin motors. This paper extends the aforementioned theoretical approach by allowing for a distribution of kinesin motor velocities; the distribution is described by a probability density function (PDF). For a two kinetic state model (that accounts for the pausing and running populations of CEs) an analytical solution describing the propagation of the CE concentration wave is derived. Published experimental data are used to obtain an analytical expression for the PDF characterizing the kinesin velocity distribution; this analytical expression is then utilized as an input for computations. It is demonstrated that accounting for the kinesin velocity distribution increases the rate of spreading of the CE concentration waves, which is a significant improvement in the two kinetic state model.