NiFe／Co／Cu／Co结构自旋阀GMR效应及Co夹层的影响研究

用射频磁控溅射发射法成功制备了ＮｉＦｅ／Ｃｕ／Ｃｏ自旋阀多层膜材料,改变Ｃｕ层的厚度,研究材料的ＧＭＲ效应与Ｃｕ层厚度的关系,结果表明Ｃｕ为２．５ｎｍ时样品的ＭＲ值最大,其磁电阻效应ＭＲ可达１．６％,在ＮｉＦｅ和Ｃｕ之间插入一Ｃｏ薄夹层,通过对不同温度厚度Ｃｏ夹层的样品的ＭＲ曲线及磁滞回线的研究,讨论了Ｃｏ夹层对样品磁电阻的影响并分析了原因,结果表明插入适当的Ｃｏ层将提高材料的磁电阻效应,可达２．     

淀积磁场对NiO／Ni81Fe19双层膜特性的影响

用射频磁控溅射法在外磁场中淀积 Ｎｉ Ｏ／ Ｎｉ８１ Ｆｅ１９ 双层膜, 利用淀积磁场（ Ｈｄｅ） 诱导易轴并确定交换耦合场方向． 研究了淀积磁场对 Ｎｉ Ｏ／ Ｎｉ Ｆｅ 双层膜特性的影响, 结果表明, 淀积磁场改善了双层膜的磁滞回线的矩形度, 减小矫顽力, 增强交换耦合作用． 反铁磁性层 Ｎｉ Ｏ 和铁磁性层 Ｎｉ Ｆｅ 的厚度对矫顽力和交换耦合作用有很大的影响． 在５６ｋ Ａ／ｍ 的磁场中制备的 Ｎｉ Ｏ （５０ｎｍ） ／ Ｎｉ Ｆｅ （２５ｎｍ） 双层膜的易轴矫顽力 Ｈ Ｃ为１ ． ９ｋ Ａ／ｍ , 交换耦合场 Ｈ Ｅ Ｘ为２ ． ６ｋ Ａ／ｍ , 临界温度 Ｔｃ 为１５０ ℃, 截止温度 Ｔ Ｂ为２３０ ℃     

交换耦合NiFe／TbCo双层膜的铁磁共振研究

本文用铁磁共振（ＦＭＲ）方法研究了ＮｉＦｅ／ＴｂＣｏ双层膜的交换耦合作用，其铁磁共振波谱显示出共振吸收与耦合作用间的紧密联系。交换耦合作用场增大，自旋波共振模式向一致共振峰模式退化，而一致共振线宽与交换耦合场存在着线性关第，直至自旋共振峰消失，而一致共振线宽达最大值。这些现象可用我们建立的简单磁化强度作半抛物线型变化的模型进行解释，实验与理论基本吻合。说明由于ＴｂＣｏ膜的耦合作用，ＮｉＦｅ膜的磁化     

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。     

NiFe和NiFe／Cr／NiFe薄膜的磁电阻特性与膜厚关系

本文研究了采用离子束溅射技术制备的ＮｉＦｅ薄膜及层状结构ＮｉＦｅ／Ｃｒ／ＮｉＦｅ薄膜的磁电阻特性与膜厚的关系。用四探针法测量薄膜的磁电阻。由实验结果得到磁电阻特性和膜厚及Ｃｒ夹层厚度的关系。分析了ＮｉＦｅ／Ｃｒ／ＮｉＦｅ膜中两层ＮｉＦｅ膜之间存在在反铁磁交换耦合时，磁电阻效为著增强的现象，ＮｉＦｅ／Ｃｒ／ＮｉＦｅ膜各向异性磁电阻系数△ρ／ρａｖ达５．１％。     

NiO／NiFe双层膜的制备及其交换耦合作用研究

用直流磁控反射溅射制备ＮｉＯ／ＮｉＦｅ双层膜。在保持ＮｉＦｅ层的厚度２０ｎｍ不变的条件下，发现尽管没有用外加磁场引导单向各向异性，由于底盘旋转等因素的影响，ＮｉＯ（７０ｎｍ）／ＮｉＦｅ（２０ｎｍ）双层结构仍显示较好的单向各向异性，交换耦合场可达３０Ｏｅ以上。通过改变ＮｉＯ层的厚度，溅射气体Ａｒ分压以及溅射气体与反应气体的比例Ａｒ／Ｏ２，研究了反铁磁层厚度以及溅射条件对交换耦合场的影响。     

Cu层和Mo层对NiFe多层膜巨磁电阻（GMR）的影响

采用磁控溅射方法制备了ＮｉＦｅ／Ｃｕ和ＮｉＦｅ／Ｍｏ两个系列的多层膜，进行了结构，磁性和磁电阻测量，并对部分ＮｉＦｅ／Ｃｕ多层膜样品作了电镜分析，对于ＮｉＦｅ／Ｃｕ多层膜，在室温下的测量到巨磁电阻随Ｃｕ层厚度振荡的第一，二三峰。在ＮｉＦｅ／Ｍｏ多层膜样品中未发现巨磁电阻效应，讨论了非磁性 多层膜的磁性，界面结构和巨磁电阻效应。     

磁性多层膜的Ф射线光电子能谱研究

用射频／直流磁控溅射法制备了ＮｉＯｘ／Ｎｉ８１Ｆｅ１９和Ｃｏ／ＡｌＯｘ／Ｃｏ磁性薄膜。利用Ｘ射线光电子能谱研究了ＮｉＯｘ对Ｎｉ８１Ｆｅ１９耦合交换场Ｈｅｘ与ＮｉＯｘ化学状态的关系以及Ｃｏ／ＡｌＯｘ／Ｃｏ磁性薄膜中ＡｌＯｘ对Ｃｏ膜的覆盖状况。结果表明：Ｈｅｘ的大小只与＋２价镍有关,单质镍和＋３价镍对Ｈｅｘ没有什么作用;在Ｃｏ／ＡｌＯｘ／Ｃｏ磁性薄膜中,Ａｌ层将Ｃｏ膜完全覆盖所需的要最小厚度为２．０ｎ     

NiFe／Cu多层膜的热处理研究

针对用磁控溅射方法制备的ＮｉＦｅ／Ｃｕ多层膜进行了热处理研究，经退火后，ＮｉＦｅ／Ｃｕ多层膜的磁电阻有了显著的变化，在２５０℃的最佳退火下，最大磁电阻变化率为５．２％。     

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     

基于NiFeCo/Cu多层膜巨磁电阻效应的磁微球检测

分析了应用于磁性生物检测的GMR传感器的工作原理.直流磁控溅射法制备了Ni65Fe15CO20/Cu多层膜,研究了室温下多层膜的GMR效应对缓冲层(NiFeCo)厚度、间隔层(Cu)厚度及铁磁层(NiFeCo)厚度等参数的依赖关系,得到了GMR值达8.8%的多层膜样品:缓冲层(NiFeCo)5nm,间隔层(Cu)2.4nm,铁磁层(NiFeCo)1.6nm,且饱和场低、磁滞小、灵敏度较高,符合磁性生物检测技术的要求.制备了基于优化参数NiFeCo/Cu多层膜的GMR传感器,对器件的性能进行了测试,结果表明所制备的GMR传感器能够检测磁微球.     

生物传感用巨磁电阻传感器及其磁珠检测性能

本文采用直流磁控溅射沉积了结构为NiFeCo(缓冲层)/[Cu/NiFeCo]×10/ Ta,巨磁电阻(GMR)值为9.8%的多层膜,利用微细加工技术制备了基于此GMR多层膜的生物传感器,GMR电阻线条的线宽分别为3μm和5μm.测试了单个GMR传感器的特性,并将该传感器件和外接可调电阻组成惠斯通电桥,采用该GMR电桥对Dynal公司的MyOne磁珠进行了检测.分别测试了施加变化垂直磁场和施加间歇式恒定垂直磁场时GMR电桥信号对传感器表面覆盖磁珠的响应,研究了GMR电桥信号和磁珠覆盖率的关系.选用器件电阻线宽分别为3μm和5μm的传感器测试了器件线宽对传感器灵敏度的影响.结果表明,GMR传感器能够检测到磁珠的存在,最低能检测的磁珠数量约100个,且GMR电桥信号与磁珠覆盖率基本成正比,器件的灵敏度与传感器线宽基本成反比.     

Magnetoresistance behaviour in CoFe/Cu multilayers: thin Cu layer effect

The magnetoresistance properties of the CoFe/Cu multilayers have been investigated as a function of thin non-magnetic Cu layer thickness (from 2.5 to 0.3 nm). CoFe/Cu multilayers were electrodeposited on Ti substrates from a single electrolyte containing their metal ions under potentiostatic control. The structural analysis of the films was made using X-ray diffraction. The peaks appeared at 2θ ≈ 44°, 51°, 74° and 90° are the main Bragg peaks of the multilayers, arising from the (111), (200), (220) and (311) planes of the face-centered cubic structure, respectively. The magnetic characterization was performed by using vibration sample magnetometer in magnetic fields up to ±1600 kA/m. At 0.6, 1.2 and 2.0 nm Cu layer thicknesses, the high saturation magnetization values were observed due to antiferromagnetic coupling of adjacent magnetic layers. Magnetoresistance measurements were carried out using the Van der Pauw method in magnetic fields up to ±1000 kA/m at room temperature. All multilayers exhibited giant magnetoresistance (GMR), and the similar trend in GMR values and GMR field sensitivity was observed depending on the Cu layer thickness.     

Influence of antiferromagnetic FeMn on magnetic properties of perpendicular magnetic thin films

We studied the influence of an anitferromagnetic FeMn layer on perpendicular magnetic anisotropy (PMA) and perpendicular coercivity (H_C⊥) of the CoCr/Pt multilayers and found that both PMA and H_C⊥ can be enhanced by the FeMn layer. We observed an obvious exchange coupling between FeMn and CoCr/Pt multilayers which enhances PMA and may increase the density of pinning sites that can pin the domain wall of ferromagnetic layers and lifts up energy barrier during the propagation of domain walls. This leads to the enhancement of H_C⊥. Moreover, X-ray diffraction results shows that the (111) texture of the FeMn layer enhances that of the CoCr/Pt multilayers, leading to the increase of PMA and H_C⊥ as well. This result is of great significance on improving magnetic properties of perpendicular magnetic recording media by using an antiferromagnetic manganese alloy.     

Microstructure,Magnetic and Magnetoresistance Properties of Electrodeposited [Fe/Pt] Granular Multilayers

In this paper, we report experimental results concerning the magnetic properties and the magnetoresistance effect of [Fe/Pt] _n and [Pt/Fe] _n electrodeposited multilayers. Two series of multilayers starting with Pt and Fe layers, respectively, were grown onto glass substrate covered with electroless deposited amorphous Ni. We investigated the effect of the seed layer (Pt or Fe) and Pt layer thicknesses on the magnetic and magnetoresistance properties of electrodeposited multilayers. The structure and morphology of the samples were characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM). The hysteresis loops of the [Fe/Pt] _n and [Pt/Fe] _n multilayers showed that the magnetic properties strongly depend on the Pt thickness and on the seed layer (the first layer deposited onto the glass substrate). [Fe/Pt] _n and [Pt/Fe] _n electrodeposited multilayers display magnetoresistance (∼15%) effect which can be explained mainly by the spin-dependent scattering of conduction electrons between Fe layers through a Pt layer and by the existence of anti-ferromagnetic coupling between subsequent Fe layers. The existence of a GMR effect in Fe/Pt multilayers is very promising for technological applications (e.g., magnetoresistance sensors).     

Effect of Co Ion Implantation on GMR of [NiFeCo(10 nm)/Ag(10 nm)]×20 Multilayer Film

The composition, phase structure and microstructure of the discontinuous multilayer film [NiFeCo(10 nm)/ Ag(10 nm)]×20 were investigated after Co ion implantation and annealing at 280, 320, 360 and 400℃, respectively. GMR (giant magnetoresistance) ratio of the film with/without Co ion implantation was measured. The results showed that Co ion implantation decreased the granule size of the annealed multilayer film, and increased Hc value and GMR ratio of the multilayer film. After annealing at 360℃, the multilayer film [NiFeCo(10 nm)/Ag(10 nm)]×20 with/without Co ion implantation both exhibited the highest GMR ratio of 12.4%/11% under 79.6 kA/m of applied saturation magnetic field.     

The effect of Fe content in electrodeposited CoFe/Cu multilayers on structural, magnetic and magnetoresistance characterizations

A series of CoFe/Cu multilayers were electrodeposited on Ti substrates from the electrolytes containing their metal ion under potentiostatic control, but the Fe concentration in the electrolytes was changed from 0.0125 M to 0.2 M. The deposition was carried out in a three-electrode cell at room temperature. The deposition of Cu layers was made at a cathode potential of -0.3 V with respect to saturated calomel electrode (SCE), while the ferromagnetic CoFe layers were deposited at -1.5 V versus SCE. The structural studies by X-ray diffraction revealed that the multilayers have face-centered-cubic structure. The magnetic characteristics of the films were investigated using a vibrating sample magnetometer and their easy-axis was found to be in film plane. Magnetoresistance measurements were carried out using the Van der Pauw method at room temperature with magnetic fields up to +/- 12 kOe. All multilayers exhibited giant magnetoresistance (GMR) and the GMR values up to 8% were obtained.     

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.     

GMR multilayers and head design for ultrahigh density magneticrecording

This paper describes materials development, device modeling, and initial test results for a novel GMR reproduce head for ultrahigh density recoding (~ 10 Gbit/in²). It consists simply of a 20-bilayer GMR multilayer, self-stabilized by intrinsic antiferromagnetic interlayer coupling, and self-biased by sense current into a bipolar, field-gradient-sensing bias state. Analogous to a dual magnetoresistive (DMR) such a GMR-DMR head is capable of achieving very high linear resolution without shields. Tape-test results using evaporated NiFe/Cu and sputtered NiFeCo/Cu agree reasonably well with theoretical expectations. 1/f noise in these GMR multilayers will also be discussed     

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．