具有覆盖层的Co/Cu/Co三明治的巨磁电阻效应研究

研究了覆盖层为铁磁性的Fe和非铁磁性的Ti、Cu的Co/Cu/Co三明治在室温和低温下的巨磁电阻效应。实验结果表明,室温下有覆盖层时,Co/Cu/Co三明治的巨磁电阻效应值没有明显变化,但以Fe为覆盖层的样品的矫顽力和饱和场明显减小,而Ti、Cu覆盖层对三明治样品的矫顽力和饱和场无太大的影响。温度降低时,覆盖层使Co/Cu/Co三明治的巨磁电阻值显著增加,表明样品的巨磁电阻效应与覆盖层及其与上层Co所形成的界面密切相关。     

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。     

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．     

Co／Cu／Co三明治膜的巨磁电阻效应研究

采用超高真空电子束蒸发方法在硅单晶衬底上制备了Ｃｏ／Ｃｕ／Ｃｏ三明治膜,研究了衬底晶向、过渡工层材料和生长室温度对三明治膜中巨磁电阻效应的影响;结合原子力显微镜表面形貌观察,探讨了三明治膜表面（界面）组糙度与其巨磁电阻效应的内在关系;还分析了三明治膜经高温热退火后巨磁电阻效应退化的物理机制。     

Si作过渡层的Co／Cu／Co三明治膜中高灵敏度巨磁电阻效应？…

用高真空电子束蒸发方向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是性。在Ｓｉ １５ｎｍｍ／ｃｏ５ｎｍ／Ｃｕ３ｎｍ／Ｃｏ５ｎｍ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     

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%.     

Co/Ni多层膜的热处理研究

采用磁控溅射方法制备了Co/Ni多层膜并做了热处理,测量了系列样品的结构,磁性和磁电阻,受热处理条件等因素影响,多层膜的层间磁性耦合性质发生变化,电阻率下降,而其各向异性磁电阻的数值没有一致的变化趋势,讨论了磁性层织构和界面对多层膜的磁性和各向异性磁电阻效应的影响。     

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。     

C/Co/C纳米颗粒膜的制备及特性

应用对靶磁控溅射法在玻璃基底上制备了类三明治结构C/Co/C纳米颗粒膜,并进行了原位退火.发现磁性层厚度对C/Co/C颗粒膜的微结构和磁特性有明显影响.在400℃退火的样品具有很好的六角密堆积结构,磁矩很好的排列在膜面内.随着磁性层Co层厚度的增加,矫顽力Hc先增大然后减小,粒径和磁畴簇略微增大,样品的表面粗糙度Ra也减小到了0.5 nm左右.     

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。     

Magnetic and Structural Properties in Co/Cu/Co Sandwiches with Ni and Cr Buffer Layers

1. IntroductionThe gial magnetoresistance (GMR) effect occursin multilayers of ferromagnet ic / nonmagnet ic met almultilayers and sandwiches[1'2]. Many material systems, such as Fe/Crl'], Co/Cut'l, have exhibited theGMR properties. The saturation field in these multilayers is usually very large due to the strong exchange coupling field between the adjacent magneticlayers. Non-coupled type multilayers consisting of twomagnetic components with different coercive forces,and relatively thick …     

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．     

Giant Magnetoresistance Effect of [bcc-Fe(M)/Cu](M=Co,Ni) Multilayers

1. IlltroductionGiant magnetoresistance (GMR) effect of metallic multilayers has been widely investigated after thefinding by Baibich et al.11], as a new phenomenon tobreak through the memory density in ultra high density magnetic recording, high sensitivity in magnetichead, and so on. Metallic multilsyers of 3d transition elements could be classified into three groups of[bee/bcc], [fee/fccl and [bee/fcc] from the standpointof combination of crystal structure of constituting elements of metal…     

Influence of a Pb buffer layer on structural and magnetotransport properties of Co/Cu multilayers

In this paper changes of structure and magnetotransport properties of Co/Cu multilayers were observed as a function of the Pb buffer layer thickness. Structural analysis indicated that the Pb buffer leads to the decay of superlattice periodicity. Surface topography of the top layer of the Co/Cu multilayers observed by SFM allowed the determination of surface roughness which is relatively large and weakly depends on buffer thickness. This effect is accompanied by the continuous rise of island size that reaches a diameter around 200 nm for Co/Cu multilayers deposited on 40 nm Pb buffer. AES experiments show significant segregation of Pb to the surface. A small magnetoresistance effect ΔR/R measured for Co/Cu multilayers deposited on an Pb buffer is almost independent of the thickness of the buffer layer. This behavior of ΔR/R could be understood by assuming that discontinuous ferromagnetic layers, bridged through the Cu spacer, are formed.     

Interlayer couplings and magnetoresistance effects of Fe/Cr/Fe/Ni-Fe/NiO sandwiches

Interlayer coupling between Fe layers and magnetoresistance effect have been investigated in Fe/Cr/Fe/Ni-Fe/NiO sandwiches. The interlayer coupling between two Fe layers oscillates as the thickness of Cr layer changes. The strongest antiferromagnetic coupling is observed when the thickness of the Cr layer is 1.2 nm. The highest magnetoresistance ratio due to spin-dependent scattering is only 0.13%. The low magnetoresistance ratio is thought to be caused by high resistivity of the Cr layer. This revised version was published online in November 2006 with corrections to the Cover Date.     

Magnetoresistance and microstructure evolution upon rapid thermal annealing of giant magnetoresistive Co/Cu/Co/CoNbZr multilayers

The magnetoresistance (MR) variation of Co/Cu/Co/CoNbZr spin valves as a result of rapid thermal annealing has been investigated. MR ratio of 3.8% was obtained in the as-deposited sample and a considerable increase to 6.86% was observed in the 450°C×60 s treated sample. Microstructure studies show that the enhancement of MR ratio is a consequence of the nano-crystallization of amorphous CoNbZr soft layer. The nano-crystallized CoNbZr possess fine and dense microstructure and excellent electrical and soft magnetic properties which leads to the MR enhancement. With increasing annealing temperature or annealing time, interface roughness caused by rapid grain growth decrease the MR ratio rapidly. XRD studies imply that the interfusion of Cu atom into the Co layer is another possible degradation mechanism of Co/Cu/Co/CoNbZr spin valves at annealing temperature beyond 550°C.     

Giant magnetoresistance increase in a hard–soft spin valve structure with the growth of a semiconductor layer

Magnetic and transport properties of a hard–soft spin valve structures have been investigated. A first series of sandwiches composed of an artificial antiferromagnetic (AAF) Co/Ru/Co sandwich decoupled from a soft Fe/Co buffer layer as follows: Fe_{50 Å}/Co_{5 Å}/Cu_{30 Å}/Co_{30 Å}/Ru_{5 Å}/Co_{30 Å}/Cu_{20 Å}/Cr_{20 Å} has been prepared. This sandwich presents a giant magnetoresistance (GMR) of 1.7% and an exchange coupling strength of approximately −1.73 erg/cm². Afterwards, we have grown a second series of sandwiches in which the Cu/Cr capping layer has been replaced by a 15-Å thin semiconductor layer of ZnS, covered by a soft ferromagnetic layer of Co_{5 Å}/Fe_{50 Å}. Surprisingly, the giant magnetoresistance for the last sandwiches has been increased by a factor of 2, up to 4%. To explain this non-expected result, we have performed atomic force microscope imaging at the semiconductor layer surface. The results show that the semiconductor layer is not homogeneous and contains a non-negligible density of pin-holes, that are responsible of a direct magnetic coupling between the upper 30 Å Co layer of the AAF and the Co 5 Å/Fe 50 Å bilayer. This coupling induces a strong asymmetry between the magnetic layers of the AAF and consequently an enhancement of the GMR.