磁性多层膜的正巨磁电阻特性

采用离子束溅射方法制备了正巨磁电阻多层膜，在制备过程中采用外加磁场和退火处理。在室温条件下多层膜的巨磁电阻效应达到200％～300％，并用磁矩取向的双电流导电模型对正磁电阻的机理进行了解释。     

自旋相关隧道磁电阻效应研究进展

自旋隧道磁电阻与多层膜巨磁电阻相比，磁电阻具有工作外场低、灵敏度高、温度系数小等特点，因而在磁电子器件应用中受到人们的重视。作为隧道磁电阻的基础，首先介绍了与隧道磁电阻紧密相关的自旋极化和自旋相关输运特点，然后着重阐述了磁性隧道结、铁磁金属颗粒膜、纳米多晶的隧道磁电阻效应的原理和最新研究进展，最后提出目前隧道磁电阻研究中存在的问题并对其发展作了展望。     

NiFe/Ag多层膜在低场下的巨磁电阻行为

用磁控溅射法制备了NiFe/Ag多层膜 ,并从实用角度对NiFe/Ag多层膜的低场巨磁电阻效应作了研究。分析了该膜系列产生低场巨磁电阻效应的机理 ,并进行了实验研究 ,最终获得在低场 (小于 79 6× 2 5 0A/m)常温下有高达 5 0 %巨磁电阻效应的材料     

流动槽滴入法电结晶制备铜钴纳米多层膜

在硼酸镀液体系中采用流动槽滴入法电结晶制得Cu/Co纳米多层膜,通过循环伏安法确定Cu、Co电结晶电位,分别为-0.55V和-1.05V(vs.SCE),通过X射线衍射技术(XRD)和X射线荧光光谱法(XRF)对Cu/Co纳米多层膜的结构、成份进行了分析.并用物性测量系统PPMS测试了Cu/Co多层膜的磁性能,结果表明:电结晶制备的Cu/Co多层膜的矫顽力比较小,仅为34 Oe,适合作巨磁阻磁头材料,其磁电阻随磁场强度的增大而减小,且约在3000 Oe时磁电阻趋于饱和,此时的巨磁阻效应GMR值达到了14%.     

Si作过渡层的Co/Cu/Co三明治膜中高灵敏度巨磁电阻效应和平面内磁各向异性

用高真空电子束蒸发方法制备了以半导体材料Ｓｉ 为过渡层的Ｃｏ／Ｃｕ／Ｃｏ三明治膜并研究了其巨磁电阻效应。当Ｓｉ 过渡层厚度达到０．９ｎｍ 时,三明治膜中开始出现较强的平面内磁各向异性。在Ｓｉ１．５ｎｍ／Ｃｏ ５ｎｍ／Ｃｕ ３ｎｍ／Ｃｏ ５ｎｍ结构中,在其易轴上得到了５ ．５％ 的巨磁电阻值和０．９ ％／Ｏｅ 的高磁场灵敏度。研究了过渡层Ｓｉ／Ｃｏ 界面之间的相互扩散,发现在过渡层Ｓｉ 与Ｃｏ 层间形成了ＣｏＳｉ 化合物。这个硅化物界面层诱导了三明治膜的平面内磁各向异性,从而导致了易轴上高灵敏度巨磁电阻效应。     

巨磁电阻多层结构——从多层膜到多层纳米线

综述了巨磁电阻多层膜（包括连续多层膜,不连续多层膜,颗粒膜,非匀相合金膜及层状与粒状混合型多层膜）研究的一些结论,着重评述了巨磁电阻多层纳米线的研究进展,包括其制备,表征,传输性能的测定方法,电流垂直于膜面的巨磁电阻（CPP－GMR）,及如何利用多层纳米线的CPP－GMR测定材料的自旋扩散长度和自旋散射不对称因子等材料常数。简要介绍了开发前景。     

质子辐照对多层膜巨磁电阻结构磁性能的影响

研究了质子辐照对多层膜巨磁电阻结构磁性能的影响。利用5 MeV的不同辐照剂量和剂量率的质子对磁控溅射法制备的CoFe/(CoFe/Cu)₁₀/CoFe/Ta多层膜巨磁电阻结构进行辐照实验。XRD分析表明质子辐照没有改变CoFe/Cu的晶格结构。分析磁滞回线和磁电阻曲线得知在实验选取的辐照剂量范围内, 饱和磁化强度和本征电阻随着辐照剂量的增加而增加, 而矫顽场和磁电阻率随剂量的增加而减小。利用质子辐照对自旋相关散射、平均自由程的影响解释了本征电阻的变化, 并基于二流体模型对磁电阻率的变化进行了分析。由此得出, 多层膜巨磁电阻结构具有一定的抗辐照能力。     

NiFe／Cu和NiFe／Mo多层膜的界面结构与巨磁电阻

采用磁控溅射方法制备了ＮｉＦｅ／Ｃｕ和ＮｉＦｅ／Ｍｏ多层膜。测量了厚度不同的Ｃｕ层和Ｍｏ层多层膜的磁性和磁电阻,并用电镜分析了部分ＮｉＦｅ／Ｃｕ多层膜样品。测量到ＮｉＦｅ／Ｃｕ多层膜的室温巨磁电阻随Ｃｉ层厚度振荡的第一、二、三峰。而在ＮｉＦｅ／Ｍｏ多层膜中未发现巨磁电阻效应。讨论了多层膜的界面结构对巨磁电阻效应的影响。     

金属颗粒膜巨磁电阻效应的机制和影响因素

由于巨磁电阻效应在磁记录设备和传感器的潜在应用，具有该效应的材料得到了广泛地研究。特别是继金属多层膜之后的金属磁性颗粒膜，由于其制备简单，巨磁电阻效应的机理较为复杂，受到人们的青睐。本文综述了金属磁性颗粒膜中巨磁电阻效应的自旋相关散射机制和影响因素。在此基础上，指出了当前值得注意的研究方向。     

不同制备条件下的Co/Cu多层膜的巨磁电阻及铁磁共振研究

用溅射方法制备了几批Co／Cu多层膜和夹层膜样品,通过测试发现：Co／Cu多层膜样品的巨磁电阻与制备条件有关。在较高本底真空和较低工作气压条件下制备的样品具有较大的巨磁电阻,其铁磁共振测试的结果和Heinrich的夹层膜的理论计算结果相吻合．     

磁电阻材料及其应用的研究进展

本文综述了磁电阻 (MR)材料的研究进展 ,并对目前研究热点的四类巨磁电阻 (GMR)材料进行了概括评述 ,侧重论述MR材料在信息存储等领域的应用 ,明确指出开发和应用MR材料的关键问题是提高各类GMR材料的室温MR值和降低其工作磁场     

不同磁相纳米颗粒膜的巨磁电阻

用玻恩(Born)散射方法计算了具有两类不同磁相的颗粒膜的巨磁电阻(GMR),结果表明,在低温(4.5K),小磁性颗粒(包含原子数n ≤12)对巨磁电阻只有很小的贡献,巨磁电阻值随颗粒包含原子数的增多而增加.在室温下,巨磁电阻主要由大磁性颗粒(n≥12)产生.理论计算较好地解释了实验所观测到的结果.     

Giant magnetoresistance in electrodeposited Co-Ag granular films

We report on the electrodeposition of Co-Ag granular films with GMR from a chloride-based electrolyte. Two different electrochemical techniques (chronoamperometry and pulse plating) were used to prepare the films. Both electrochemical and TEM analysis have revealed the heterogeneity of the as-deposited samples. GMR values up to 7% at room temperature were measured. The longitudinal (LMR) and transverse (TMR) magnetoresistance were practically indistinguishable indicative of real granular systems. An appropriate numerical analysis of the magnetoresistance curves showed high superparamagnetic contribution to the total MR.     

多晶La-Pb-Mn-O体材料的巨磁电阻效应

利用固相反应法制备了多晶立方结构的Ｌａ－Ｐｂ－Ｍｎ－Ｏ体材料,材料的铁磁相变温度ＴＣ为２５７Ｋ,其金属－半导体转变温度ＴＰ为２５１Ｋ,外加磁场分别为５Ｔ和１３Ｔ时,材料的巨磁电阻（ＧＭＲ）峰值分别达到了７２％和８５％,在７７Ｋ￣室温的温度范围内,材料都具有ＧＭＲ效应,ＴＰ附近具有ＧＭＲ峰值效应,ＧＭＲ效应与自旋极化行为有关,而ＴＰ附近的ＧＭＲ峰值效应除了与自旋极化子行为有关外,与磁场作用下勒流子自     

Characterizations of NiCu/Cu Multilayers: Dependence of Nonmagnetic Layer Thickness

A series of NiCu/Cu multilayers were grown on (110) textured polycrystalline Cu substrates from a single electrolyte under potentiostatic deposition conditions. Microstructure, magnetoresistance and magnetic properties of the multilayers were investigated as a function of the nonmagnetic layer thicknesses. The structural studies by X-ray diffraction revealed that the multilayers have face-centered-cubic structure with preferred (110) crystal orientation as their substrates. The composition of the deposits determined by energy dispersive X-ray spectroscopy showed that the Cu content of the films increased as the Cu layer thickness increased. The scanning electron microscope studies showed that samples have homogeneous and smooth surfaces. Multilayers exhibited either anisotropic magnetoresistance (AMR) or giant magnetoresistance (GMR) depending on the non-magnetic Cu layer thickness. The multilayers with Cu layer thickness thicker than 0.7 nm exhibited GMR, but the AMR effect was observed to be dominant for the Cu layer thickness less than 0.7 nm. The GMR curves are broad in shape and the nonsaturated curves indicated the predominance of a superparamagnetic contribution. The GMR magnitudes of NiCu/Cu multilayers are found to be about 1–1.5 %. The vibrating sample magnetometer measurements revealed that the saturation magnetization decrease with increasing nonmagnetic layer thickness. The changes in the magnetic and magnetotransport properties might arise from the change in the Ni and Cu content of the samples caused by the variation of Cu layer thicknesses.     

Giant magenetoresistive sensors. 2. Detection of biorecognition events at self-referencing and magnetically tagged arrays

Microfabricated devices formed from alternating layers of magnetic and nonmagnetic materials at combined thicknesses of a few hundred nanometers exhibit a phenomenon known as the giant magnetoresistance effect. Devices based on this effect are known as giant magnetoresistive (GMR) sensors. The resistance of a GMR is dependent on the strength of an external magnetic field, which has resulted in the widespread usage of such platforms in high-speed, high-data density storage drives. The same attributes (i.e., sensitivity, small size, and speed) are also important embodiments of many types of bioanalytical sensors, pointing to an intriguing opportunity via an integration of GMR technology, magnetic labeling strategies, and biorecognition elements (e.g., antibodies). This paper describes the utilization of GMRs for the detection of streptavidin-coated magnetic particles that are selectively captured by biotinylated gold addresses on a 2 x 0.3 cm sample stick. A GMR sensor network reads the addresses on a sample stick in a manner that begins to emulate that of a "card-swipe" system. This study also takes advantage of on-sample magnetic addresses that function as references for internal calibration of the GMR response and as a facile means to account for small variations in the gap between the sample stick and sensor. The magnetic particle surface coverage at the limit of detection was determined to be approximately 2%, which corresponds to approximately 800 binding events over the 200 x 200 microm capture address. These findings, along with the potential use of streptavidin-coated magnetic particles as a universal label for antigen detection in, for example, heterogeneous assays, are discussed.     

巨磁电阻在计算机存储领域的应用

用巨磁电阻（GMR）材料的构成的磁电子学新器件,已开始在计算机存储领域成功地获得了应用,介绍了用于计算机硬盘驱动器的巨磁电阻磁头和巨磁电阻随机存储存储器,描述了它们的工作原理,性能特点及研究现状和发展趋势。     

Transition of the magnetotransport in a Co-TbN system

Unexpected magnetism is investigated by measurements of the magnetic and magneto-transport properties in the two phase-separated thin films of nano-sized TbN clusters embedded in Co matrices. The spin-dependent transport depends strongly on the volume fraction of magnetic TbN clusters, especially on the continuity of the magnetic phase. With decreasing the TbN volume fraction, the giant magnetoresistance (GMR) is reduced and the anisotropic magnetoresistance (AMR) is enhanced. Unlike the GMR observed in Co68(TbN)32, the AMR is found in Co72(TbN)28. The room-temperature magnetization exhibits a typical ferromagnetic signal mainly due to the Co matrix, while the low-temperature magnetization shows an additional linear magnetic component. This is attributed to the magnetic moment of TbN at temperatures below the ferromagnetic transition temperature T(C) = 44 K, and the magnetic moments of TbN are coupled with those of Co. The topological and magnetic images support the magnetic exchange at the boundary between the TbN clusters and the Co matrix.     

巨磁电阻材料A0.05Co0.95Cr2S4(A=Zn、Ni、Cd、Fe)的输运行为及磁性能研究

过渡金属尖晶石型硫化物具有包括超巨磁电阻(CMR)效应在内的多种物理性能, 其CMR效应机理的研究对开发巨磁电阻材料有重要价值。目前, 铬基硫族尖晶石的CMR效应尚未深入研究。本论文通过固相反应法制备A_0.05Co_0.95Cr₂S₄(A=Zn、Ni、Cd、Fe)样品, 研究磁性和非磁性元素掺杂对CoCr₂S₄晶体结构和磁性能的影响。XRD检测表明, 掺杂的A_0.05Co_0.95Cr₂S₄(A=Zn、Ni、Cd、Fe)均呈现纯的尖晶石结构, 掺杂导致的晶胞参数变化与掺杂元素的离子半径成比例。磁电阻测定表明A_0.05Co_0.95Cr₂S₄(A=Zn、Ni、Fe)均具有巨磁电阻效应。掺杂削弱了铁磁相互作用, 导致A_0.05Co_0.95Cr₂S₄(A=Zn、Ni、Cd、Fe)的居里温度T_C降低。在0.01 T下, A_0.05Co_0.95Cr₂S₄(A=Zn、Ni、Cd、Fe)的零场冷却(ZFC)和加场冷却(FC)曲线均呈现磁性不可逆现象。A_0.05Co_0.95Cr₂S₄(A=Zn、Ni、Cd、Fe)呈现典型的亚铁磁性磁滞回线, 其中Zn_0.05Co_0.95Cr₂S₄的矫顽场最大。     

GMR effect in CuCo annealed melt-spun ribbons

A thorough microstructural and magnetic analysis has been performed on as-quenched and annealed (475 and 525 degrees C, 1 hour) melt-spun Cu100-xCox (x = 10 and 15) granular alloys, presenting a giant magnetoresistance (GMR) effect. The annealed samples are inhomogeneous with respect to the Co-particle sizes and interparticles distances and, therefore, these particles present superparamagnetic and ferromagnetic behaviours, which determine the GMR response. The samples x = 15, treated at 525 degrees C during 1 hour, presented the best GMR ratio (approximately 5% at room temperature to be the highest value approaching roughly to the saturation under an applied magnetic field of 15 KOe), with the coexistence of Co-particles with both kinds of magnetic behaviour.