Perpendicular exchange bias of （Pt/Co）n/FeMn multilayers

(Pt/Co)n/FeMn multilayers with perpendicular anisotropy (PA) were prepared by magnetron sputtering with Pt as the buffer layer and the capping layer. The dependence of perpendicular exchange bias (PEB), Hex, on the thickness of the FeMn antiferromagnet (AFM) layer is similar to that of in-plane exchange bias. The value of Hex for the (Pt/Co)3/FeMn multilayer reaches 22.3 kA/m. A thin Pt spacer was inserted between the Co/FeMn interface to enhance PEB. The PEB reaches the largest at 39.8 kA/m when the thickness of the Pt spacer is 0.4 nm.     

Perpendicular exchange bias of (Pt/Co)_n/FeMn multilayers

(Pt/Co)n/FeMn multilayers with perpendicular anisotropy (PA) were prepared by magnetron sputtering with Pt as the buffer layer and the capping layer. The dependence of perpendicular exchange bias (PEB), Hex, on the thickness of the FeMn antiferromagnet (AFM) layer is similar to that of in-plane exchange bias. The value of Hex for the (Pt/Co)3/FeMn multilayer reaches 22.3 kA/m. A thin Pt spacer was inserted between the Co/FeMn interface to enhance PEB. The PEB reaches the largest at 39.8 kA/m when the thickness of the Pt spacer is 0.4 nm.     

Perpendicular magnetic anisotropy of Co85Cr15/Pt multilayers

The CoCr/Pt bilayers and (CoCr/Pt)20 multilayers with Pt underlayer were prepared by DC magnetron sputtering. The effects of prepared condition on perpendicular magnetic anisotropy were investigated. The results show that the thickness of Pt underlayer has a great effect on the microstructure and perpendicular magnetic anisotropy of CoCr/Pt bilayers and (CoCr/Pt)20 multilayers.When the thickness of Pt underlayer increases, Pt(111) and CoCr(002) peaks of both CoCr/Pt bilayers and (CoCr/Pt)20 multilayers increase and the bilayer periodicity of the multilayers is improved. The effective magnetic anisotropy of (CoCr/Pt)20 multilayers with Pt underlayer was much larger than that of CoCr/Pt bilayers. The (CoCr/Pt)20 multilayers has a stronger perpendicular magnetic anisotropy than that of CoCr/Pt bilayers. This is ascribed to the interface magnetic anisotropy of the multilayers.     

Ni/BiFeO_3超晶格磁电效应的第一性原理计算

为了探究铁磁/铁电超晶格材料的磁电耦合效应,采用基于密度泛函理论的第一性原理计算方法,研究了Ni/BiFeO_3超晶格的电子结构和磁矩.结果表明,Ni/BiFeO_3超晶格界面处Ni-3d轨道与O-2p轨道发生了强烈的电子杂化作用,Ni和BiFeO_3界面主要通过以O原子为中间媒介的电荷转移进行相互影响.在外加电场作用下,由于铁电极化的存在,超晶格结构上下两个界面存在磁化差异,原子成键和电荷转移重新分布能够引起较强的磁电耦合效应. Ni/BiFeO_3超晶格界面磁电耦合系数约为3. 509×10-~(14)T·cm~2/V.     

Perpendicular magnetic anisotropy of Co_(85)Cr_(50)/Pt multilayers

The CoCr/Pt bilayers and (CoCr/Pt)20 multilayers with Pt underlayer were prepared by DC magnetron sputtering. The effects of prepared condition on perpendicular magnetic anisotropy were investigated. The results show that the thickness of Pt under-layer has a great effect on the microstructure and perpendicular magnetic anisotropy of CoCr/Pt bilayers and (CoCr/Pt)20 multilayers. When the thickness of Pt underlayer increases, Pt(111) and CoCr(002) peaks of both CoCr/Pt bilayers and (CoCr/Pt)20 multilayers increase and the bilayer periodicity of the multilayers is improved. The effective magnetic anisotropy of (CoCr/Pt)20 multilayers with Pt underlayer was much larger than that of CoCr/Pt bilayers. The (CoCr/Pt)20 multilayers has a stronger perpendicular magnetic anisotropy than that of CoCr/Pt bilayers. This is ascribed to the interface magnetic anisotropy of the multilayers.     

XPS Studies of Magnetic Multilayers

NiOx/N81Fe19 and Co/AlOx/Co magnetic multilayers were fabricated by reactive RF/DC magnetron sputtering on clean glass substrates and oxidized Si (100) substrates, respectively. The exchange biasing field (Hex) between NiOx, and Ni81Fe19 as a function of NiOx, oxidation states was studied by X-ray photoelectron spectroscopy (XPS). The oxidation states and the oxide thickness of Al layers in magnetic multilayer films consisting of Co/AlOx/Co were also analyzed. It is found that the Hex of NiOx/Ni81Fe19 films only depends on Ni2+ but not on Ni3+ or Ni. The bottom Co can be completely covered by depositing an Al layer thicker than 2.0 nm. The oxide layer was Al2O3, and its thickness was 1.15 nm.     

Al-Al2O3-铁磁金属隧道结界面的表征

用梯形势垒模型计算偏置Al Al2 O3 铁磁金属 (Fe ,Co ,Ni和Ni80 Fe2 0 )隧道结的I V曲线 ,通过与结在 77K温度下的实验I V曲线拟合决定了结的势垒参数 .拟合结果表明 ,对于上电极为不同铁磁金属的 4种结 ,Al Al2 O3 界面处的势垒高度差别很小 ,而Al2 O3 Fe ( Co , Ni, Ni80 Fe2 0 )界面处的势垒高度以及势垒宽度则分别为 1 72eV ,1 76eV ,1 86eV ,1 6 9eV以及 1 7 6 0 ,1 1 2 2 ,1 2 2 8 ,1 3 4 0 .势垒高度和宽度因铁磁金属上电极不同而改变的现象可归因为铁磁金属原子向Al2 O3 势垒层渗透 ,以及在界面区域铁磁金属原子与Al2 O3 的氧化反应导致附加氧化势垒层的形成 .     

Dependence of domain wall structures on repetition n in[Pt（0.5 nm）/Co（0.4 nm）]n/NiO（1.1 nm）/[Co（0.4 nm）/Pt（0.5 nm）]n multilayers

The magnetic force microscopy and a sample vibrating magnetometer have been used to investigate the domain structure in two antiferromagnetically coupled Co/Pt multilayers.In the antiferromagnetic coupled[Pt(0.5 nm)/Co(0.4 nm)]_n/NiO(1.1 nm)/[Co(0.4 nm)/Pt(0.5 nm)]_n multilayers with perpendicular anisotropy,the antiferromagnetic interlayer coupling strength increases linearly with the repetition number n in Co/Pt multilayers.In demagnetized states,relatively shifted domain walls in the two Co/Pt multila...     

Interface chemical states of NiO/NiFe films and their effects on magnetic properties

Ta/NiOx/Ni81Fe19/Ta multilayers were prepared by rf reactive and dc magnetron sputtering. The exchange coupling field ( Hex) and the coercivity ( Hc) of NiOx/Ni81Fe19 as a function of the ratio of Ar to O2 during the deposition process were studied. The composition and chemical states at the interface region of NiOx/NiFe were also investigated using the X-ray photoelectron spectroscopy (XPS) and peak decomposition technique. The results show that the ratio of Ar to O2 has great effect on the nickel chemical states in NiOx film. When the ratio of Ar to O2 is equal to 7 and the argon sputtering pressure is 0.57 Pa, the x value is approximately 1 and the valence of nickel is + 2. At this point, NiOx is antiferromagnetic NiO and the corresponding Hex is the largest. As the ratio of Ar/O2 deviates from 7, the exchange coupling field ( Hex) will decrease due to the presence of magnetic impurities such as Ni +3 or metallic Ni at the interface region of NiOx/NiFe, while the coercivity ( Hc) will increase due to     

等离子喷焊层NiCrBSi+WC/Co的组织与性能

利用等离子喷焊技术在H13模具钢表面制备NiCrBSi+20%WC/Co喷焊层。研究表明,基体与喷焊层之间存在明显的分界面,与传统焊接接头的微观组织类似,喷焊层中出现垂直于界面结合方向的柱状晶,这种组织形态在等离子喷涂涂层中从未观察到,说明喷焊层NiCrBSi+20%WC/Co与H13钢基体之间的结合为冶金结合。XRD分析表明,喷焊层中的主要相为γ-(Fe,Ni),Cr7BC4,Ni4B3,Cr7C3和Co7W6,并且由于这些相的存在,使得表面喷焊层比H13钢基体具有更高的强度和硬度。     

Giant magnetoresistance effect in Ni buffered Co/Cu/Co sandwich

The effects of Ni buffer layer on the giant magnetoresistance structure of Co/Cu/Co sandwich are investigated systematically in this paper. It is found that Ni buffer layer can induce the crystallization of the lower Ni/Co layer and produce small coercivity, thus enlarging the difference in the magnetic behavior between the two magnetic layers in the sandwich. Moreover, the use of the Ni buffer layer can also improve the interface flatness in the sandwich. All these factors enhance the sensitivity of the Ni buffered sandwich.     

Comparative experiment on layered Li（Ni1/3Co1/3Mn1/3）O2 as the alternative material for LiCoO2

This work was financially supported by the National Natural Science Foundation of China （No.50472093）.     

Influence of Si buffer layer on the giant magnetoresistance effect in Co/Cu/Co sandwiches

The Co/Cu/Co sandwiches with a semiconductor Si buffer layer were prepared by high vacuum electron-beam evaporation. The influence of the Si buffer layer with different thickness on the giant magnetoresistance (GMR) effect in the Co/Cu/Co sandwiches was investigated. It was found that the GMR showed an obvious anisotropy when the thickness of Si buffer layer was larger than or equal to 0.9 nm, and that the GMR was basically isotropic with an Si buffer layer thinner than 0.9 nm. The anisotropic behavior of GMR can be ascribed to the in-plane magnetic anisotropy in the sandwiches. Due to the interdiffusion at the Si buffer/Co interface, a Co2Si interface layer with a good (301) texture formed and induced the in-plane magnetic anisotropy in the sandwiches. The dependence of the crystalline texture of the sandwiches on the thickness of Si buffer layer was also studied.     

Microstructures of NiFe/nonmagnetic metal spacer/FeMn films and their influences on exchange coupling

The discovery of the oscillatory exchange coupling between ferromagnetic (FM) layers separated by a nonmagnetic spacer layer in 1986[1] aroused peoples interest in the magnetic prop-erties of metallic multilayered films. FM/ nonmagnetic metal spacer /FM systems with any of the 3d transition metals Fe, Co and Ni or their alloys as FM material have been systematically stud-ied[24]. Oscillatory exchange coupling via spacers has been known as a general phenomenon relevant to many spacer materi…     

镍离子注入Al2O3/1Cr18Ni9Ti钎焊界面成分分析

利用扫描电镜观察了镍离子注入Ａｌ２Ｏ３／１Ｃｒ１８Ｎｉ９Ｔｉ钎焊界面的形貌,并用ｘｌⅡ能谱分析仪对焊缝进行面、线和点扫描成分分析,结果表明,焊接面非常完整,在Ａｌ２Ｏ钎焊料／１Ｃｒ１８Ｎｉ９Ｔｉ相互界面处存在着元素扩散。     

Fabrication and characterization of highly ordered Ni0.5Zn0.5Fe2O4 nanowire/tube arrays by sol-gel template method

Highly ordered nanowire/tube arrays of Ni0.5Zn0.5Fe2O4 were fabricated by the sol-gel method in the pores of anodic alu- mina membrane (AAM). Whether nanowires or nanotubes were fabricated depends on immersion time. The immersion time was 15-40 s for nanotubes and over 60 s for nanowires. The topography and crystalline structure of the nanowire arrays were character- ized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). It was found that the length and diameter of the Ni0.5Zn0.5Fe2O4 nanowires are related to the thickness of the AAM and the diameter of the pores. The results indicated that the Ni0.5Zn0.5Fe2O4 nanowires are uniform and parallel to each other.     

金属离子在Al_2O_3上的吸附机制与分布规律

对不同分布的Ｐｄ，Ｐｔ，Ｃｕ，Ｃｏ和Ｎｉ催化剂的制备因素作了研究，发现浸渍溶液的ｐＨ值对金属离子在Ａｌ２Ｏ３上的浸入深度和分布的影响最大。浸渍溶液的浓度、浸渍时间和竞争吸附剂对金属离子在Ａｌ２Ｏ３上的浸入速率和分布型式均有不同程度的影响。从吸附机理的角度对金属离子分布规律作了探讨。     

Modification of LiCo1/3Ni1/3Mn1/3O2 cathode material by CeO2-coating

Science China Technological Sciences - LiCo1/3Ni1/3Mn1/3O2 was coated by a layer of 1.0 wt% CeO2 via sol-gel method. The bared and coated LiMn1/3Co1/3Ni1/3O2 was characterized by X-ray diffraction...     

Preparation of ferromagnetic metal fine fibers by organic gel-thermal reduction process

The organic gel-thermal reduction process was used for the preparation of ferromagnetic metal Ni, Co and Fe fine fibers from the raw materials of citric acid, lactic acid and metal salts. The structure, thermal decomposition process and morphologies of the gel precursors and fibers derived from thermal reduction of these gel precursors were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, thermo-gravimetric/differential scanning calorimetry and scanning electron microscopy. The results show that spinnability of gel largely depends on molecular structure of metal-carboxylate complex that is a linear-type structure formed in the gel. As a result, the gels exhibit a good spinnability. Metal Ni, Co and Fe fine fibers are featured with diameters of around 1 μm and a high aspect ratio up to 1×106.     

低温搪瓷密着结构研究

将CoO、NiO、CuO、FeO等多种密着剂引入到搪瓷釉,采用B2O3、TiO2等取代部分SiO2、Al2O3,研制出搪瓷烧成温度低、密着性能优良的低温搪瓷。通过场发射扫描电镜和能谱仪分析表明,密着性能优良的低温搪瓷界面存在搪瓷釉层与金属铁层相互镶嵌和Fe、Si、Co、Ni、Na、K、O等元素相互扩散的中间过渡层,中间过渡层的存在为低温搪瓷产生优良密着创造条件。