NiO／Co／Cu／Co自旋阀中反铁磁NiO钉扎作用的研究

本文通过研究不同方向外加磁场下ＮｉＯ７０ｎｍ／Ｃｏ５．５ｎｍ／Ｃｕ３．５ｎｍ／Ｃｏ５．５ｎｍ自旋阀结构中磁电阻的变化,探讨了ｉＯ反铁磁层对相邻的Ｃｏ层的钉扎作用。研究发现,材料中的钉扎方向是唯一确定的,只有沿着钉扎方向增大外场,才能获得高的巨磁电阻效应和磁灵敏度。     

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。     

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     

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 ℃     

电沉积Co—Ni合金的原子探针场离子显微分析

用位置敏感原子探针场离子的显微镜（ＰｏＳＡＰ）、ＴＥＭ、ＳＥＭ等方法研究了电沉积工艺参数对Ｃｏ－Ｎｉ合金微观结构的影响，结果表明，低频脉冲直流电沉积的Ｃｏ－Ｎｉ合金的平均晶粒尺寸为７０ｎｍ，恒稳直流电沉积的晶粒尺寸为１００ｎｍ。Ｃｏ原子在沉积层中呈均匀分布，且Ｃｏ含量随电解中Ｃｏ离子浓度增加而显著增加。当电解液中ＣｏＳＯ４含量为１７．５ｇ／Ｌ时，沉积层由εＣｏ和αＣｏ两相组成，ＰｏＳＡＰ数据的三维     

交换耦全嗓层膜NiO／Ni81Fe19的基片温度效应研究

用频磁控溅射方法在不同基片温度下玻璃基片上分别制备ＮｉＯ单层膜、ＮｉＦｅ单层膜和ＮｉＯ／ＮｉＦｅ双层膜,研究了不同基片温度对膜的磁性能的影响,用振动样品磁强计（ＶＳＭ）分析了膜的磁特性,结果表明：基片温度２６０℃时淀积的ＮｉＦｅ膜矫顽力ＨＣ为１８４Ａ·ｍ＾－１,小于室温淀积ＮｉＦｅ膜的ＨＣ（５８４Ａ·ｍ＾－１）,且磁滞回线的矩形度更好,室温下淀积ＮｉＯ（５０ｎｍ）／ＮｉＦｅ（１５ｎｍ）双层膜的ＨＣ     

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     

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。     

化学沉积Ni—Mo—P合金

研究了溶液的组分及操作条件对Ｎｉ－Ｍｏ－Ｐ合金形成的影响，以得到合适的沉积工艺。试验结果表明，ＰＨ＝５．６，ｔ＝９０℃，溶液中的Ｎｉ＾２＋／ＭｏＯ４＾２－＝１３．９－１６．７；ｐＨ＝９．０，ｔ＝８５℃，Ｎｉ＾２＋／ＭｏＯ４＾２－＝２３．４－２８．５，有利于获得良好的Ｎｉ－Ｍｏ－Ｐ的合金层。     

Spin-valve heads utilizing antiferromagnetic NiO layers

Spin-valve heads utilizing antiferromagnetic NiO layers as the pinning layers were investigated. Advantages of using NiO are (1) superior corrosion resistance, (2) relatively high blocking temperature and (3) reduction in the heat generation due to current shunting. Spin-valve films of a structure of NiO/NiFe/Cu/NiFe show large Δρ/ρ (approximately 4%) and good sensitivity. Thin Co layers inserted between NiFe and Cu improve both Δρ/ρ and the thermal stability. To explore the feasibility of spin-valves with NiO, unshielded sensors with hard bias structure having longitudinally magnetized permanent magnets were fabricated. Irregular response in the transfer curves can be suppressed when the permanent magnet strength M _rt is 0.5 memu/cm² or more. The linear response region of the spin-valve sensor was optimized by adjusting the thickness of the pinned layers and the sensor height. Finally, by incorporating these results a shielded spin-valve head with a track width of 2.4 μm, a gap length of 0.3 μm and a sensor height of 0.7 μm was fabricated The response was noise-free and the output obtained with a small sense current of 0.41 mA was approximately 1 mVp-p, demonstrating a high sensitivity of a spin-valve head utilizing NiO     

Mechanisms of High Coercivity in Ni/NiO Composite Films by Post Annealing

A coercivity as large as 2.4 kOe has been achieved in the Ni/NiO composite film after an annealing under a magnetic field of 10 kOe and an O2 partial pressure of 0.001 torr. The coercivity was attributed to the strong exchange coupling of Ni and NiO. Small grain size of Ni and NiO was observed after the post-annealing. The enhanced coercivity is probably associated with the domain wall pinning by local energy minima, the distribution of Ni and NiO, and the domain structure in the interface of Ni/NiO generated under the presence of the magnetic field during the post-annealing.     

Subloop Magnetic Moment Reversal-Induced Recovery Effect in Exchange-Biased IrMn/Pt/Co/Pt Multilayers

For perpendicular exchange-biased IrMn/Pt/ Co/Pt multilayers with bidomain state, double hysteresis loops (DHLs) are achieved. It is found that exchange bias field and coercivity in full loop and two subloops’ training show different dependencies on the cycle number. Further studies show that the negative-biased (positive-biased) subloop measurement will influence training effect of the positive-biased (negative-biased) subloop, acting as a recovery process. This recovery procedure is different from the conventional ways, i.e., by applying a magnetic field perpendicular to the initial pinning direction or by leaving the sample alone for several days without any applied magnetic fields. This recovery effect can be explained by the re-rotation of antiferromagnet (AFM) spins after corresponding subloop magnetic moment reversal during the full loop measurement, which cannot happen during the subloop measurement.     

NiO／NiFeCo／Cu／NiFeCo自旋阀结构的巨磁电阻效应及影响因素的研究

用电子蒸发的方法制备ＮｉＯ／ＮｉＦｅＣ／Ｃｕ／ＮｉＦｅＣｏ自旋阀多层膜,通过磁场中退火得到好的偏置型自旋阀ＧＭＲ效应。通过对制备态以及磁场退火后样品的ＭＲ曲线的研究,讨论了交换耦合作用,单层磁性能以及层间耦合作用对材料ＧＭＲ效应的大小和磁场灵敏度的影响,得出提高交换耦合作用,改善单层磁性能和尽可能减小层间耦合将有得于得到高性能的偏置型自旋阀ＧＭＲ材料的结论。     

Exchange Bias Effect and Ferromagnetic Resonance Study of NiO/NiFe/NiO Trilayers with Different Thicknesses of NiO Layers

Antiferromagnetic (AFM₁)-ferromagnetic (FM)-antiferromagnetic (AFM₂) multilayer films are fabricated using a magnetron sputtering technique. The AFM₁, FM, and AFM₂ layers are NiO, NiFe, and NiO films, respectively, where AFM₁ and AFM₂ are of the same thickness ranging from 10 to 60 nm. The exchange bias effect and ferromagnetic resonance of NiO/NiFe (50 nm)/NiO have been investigated using the vibrating sample magnetometer (VSM) and ferromagnetic resonance (FMR) meter. Both saturation magnetization (M _s) and coercivity (H _c) increase first and then decrease with the increasing thickness of NiO layers. The maximum values (M _s = 457 kA/m, H _c = 1.86 kA/m) are achieved when the NiO thickness is 30 nm. The in-plane resonance field (H _r∥) and ferromagnetic resonance linewidth (ΔH _∥) show the lowest values (H _r = 77.4 kA/m, ΔH _∥ = 7.2 kA/m) which occur when the thickness of NiO layers is 30 nm. The dependence between exchange bias and NiO film thickness in NiO/NiFe/NiO trilayers has also been discussed.     

NiO/PB复合电致变色薄膜的制备及其性能研

采用水热法制备了垂直生长的氧化镍(NiO)纳米片薄膜, 并利用电沉积法将普鲁士蓝(PB)负载到NiO纳米片薄膜上, 制备了新型的NiO/PB复合电致变色薄膜。利用X射线衍射仪(XRD)、场发射扫描电镜(SEM)对样品的晶型以及微观形貌进行了表征, 采用紫外-可见光光度计以及电化学工作站对NiO/PB复合薄膜的电化学和电致变色性能进行了研究和表征。结果表明: NiO/PB复合电致变色薄膜具有多孔结构和较大的比表面积, 可以增大电解质与电极材料的接触面积。PB成功负载到NiO薄膜表面, 使NiO/PB复合薄膜表现出较大的电流密度。相比于单层NiO薄膜, NiO/PB复合薄膜表现出更好的电致变色性能, 其光调制范围可以达到46%, 着色效率为141 cm²/C, 并且其着色时间可以缩短到5 s, 褪色时间为6 s。     

NiO/FeCo磁性多层膜的高频磁性

制备了一系列具有铁磁/反铁磁交换偏置作用的[NiO/Fe65Co35]10多层膜,使用振动样品磁强计(VSM)测量了样品的静磁参数,利用微带线法测量了样品4GHz-10GHz的磁谱,首次制备并测得了自然共振频率(fr)在6GHz以上,最高到fr=9.6GHz的薄膜样品。结果表明交换偏置场(Hex)、各向异性场(Hua)、以及矫顽力(Hc)随铁磁层厚度(tFM)增大而减小;基于Landau-Lifishitz(L-L)方程对静磁参量和磁谱进行了比较,发现样品自然共振频率较L-L方程计算值偏大30%以上。     

Microstructure and magnetic properties of electrodeposited Co/Cu multilayer nanowire arrays

Highly uniform Co/Cu multilayer nanowire arrays had been electrodeposited into the nanochannels of porous anodic aluminum oxide template. X-ray diffraction pattern showed that Co and Cu grow in their HCP and FCC structures, respectively. Each nanowire had the same length with 20 μm and the diameter with 50 nm. The thickness of Co was 50 nm and Cu layer was about 5 nm. Magnetic measurements of the nanowire arrays showed that the magnetic coercivity for the applied field parallel to the nanowires is larger than that perpendicular to the anowires. The magnetic coercivity of Co multilayer nanowire arrays is smaller than that of the Co/Cu nanowire arrays and the crystal direction of Co layers were not obviously affected by Cu layer. The Co/Cu nanowire arrays exhibited excellent Giant Magneto Resistive ratio of about 75%.