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.     

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…     

Magnetic property and interlayer segregation in spin valve metal multilayers

The experimental results show that the exchange coupling field of NiFe/FeMn for Ta/ NiFe/FeMn/Ta multilayers is higher than that for the spin valve multilayers Ta/NiFe/Cu/NiFe/FeMn/ Ta. In order to find out the reason, the composition and chemical states at the surfaces of Ta( 12nm)/ NiFe(7nm), Ta( 12nm)/NiFe(7nm)/Cu(4nm) and Ta( 12nm)/NiFe(7nm)/Cu(3nm)/NiFe(5nm) were studied using the X-ray photoelectron spectroscopy (XPS). The results show that no elements from lower layers float out or segregate to the surface for the first and second samples. However, Cu atoms segregate to the surface of Ta(12nm)/NiFe(7nm)/Cu(3nm)/NiFe(5nm) multilayers, i.e. Cu atoms segregate to the NiFe/FeMn interface for Ta/NiFe/Cu/NiFe/FeMn/Ta multilayers. We believe that the presence of Cu atoms at the interface of NiFe/FeMn is one of the important factors causing the exchange coupling field of Ta/NiFe/FeMn/Ta multilayers to be higher than that of Ta/NiFe/Cu/NiFe/ FeMn/Ta multilayers.     

Tantalum oxide barrier in magnetic tunnel junctions

Tantalum as an insulating barrier can take the place of A1 in magnetic tunnel junctions (MTJs). Ta barriers in MTJs were fabricated by natural oxidation. X-ray photoelectron spectroscopy (XPS) was used to characterize the oxidation states of Ta barrier.The experimental results show that the chemical state of tantalum is pure Ta5~ and the thickness of the oxide is 1.3 nm. The unoxidized Ta in the barrier may chemically reacted with NiFe layer which is usually used in MTJs to form an intermetallic compound,NiTa2- A magnetic “dead layer“ could be produced in the NiFe/Ta interface. The “dead layer“ is likely to influence the spinning electron transport and the magnetoresistance effect.     

Microstructure and AMR Properties of Permalloy Films Sputtered on (Ni_ (0.81)Fe_(0.19)_ (0.66)Cr_(0.34 )Buffer

1　IntroductionTheanisotropicmagnetoresistanceeffect (AMR)waswidelystudiedinthepastyearsbecauseofitspracticalapplicationinmagneticandelectronicdevices ,eg ,themagneticsensorsandreadouthead[1 3 ] .Ni0 .81Fe0 .19hasex cellentmagneticsoftness ,andwasgenerall…     

Study on NiO/Fe interface with X-ray photoelectron spectroscopy

Different monolayers(ML)of Fe atoms were deposited on NiO(001)substrates or NiO underlayers using molecular beam epitaxy(MBE),pulse laser deposition(PLD),and magnetron sputtering(MS).The magnetic properties and microstructure of the films were studied The apparent magnetic dead layer(MDL)is found to exist at the NiO/Fe interfaces of the MBE sample(about 2 ML MDL),the PLD sample(about 3 ML MDL),and the MS sample(about 4 ML MDL).X-ray photoelectron spectroscopy indicates the presence of ionic Fe(Fe~2+ or Fe~3+ and metallic Ni at the NiO/Fe interfaces,which may be due to the chemical reactions between Fe and NiO layers.This also leads to the formation of MDL.The thickness of the MDL and the reaction products are related with the deposition energy of the atoms on the substrates.The interfacial reactions are effectively suppressed by inserting a thin Pt layer at the NiO/Fe interface.     

Study on the Properties of MetaIIophthalocyanine-Fe_3O_4 Nanoparticles Composite

The solubility , antioxidation ability, thermal stability, coercivity Hc and long term stability of MPc-Fe3O4-nanoparticles composite(M=Co, Cu, Ni, Mn) have been studied. The results show that MFc-Fe3O4 nanoparticles composite can be easily dissolved in dilute acid. The dissolving rate of different MPc-Fe3O4 nanoparticles composite is in the following order:M=Mn-M = Co相似文献   

包硅对BaCo0.8Ti0.8Fe10.4O19磁粉的磁性及粒径的影响

采用化学共沉法制备了钡铁氧体（ＢａＣＯ０．８Ｔｉ０．８Ｆｅ１０．４Ｏ１９）磁粉,研究了包硅对钡铁氧体（ＢａＣｏ０．８Ｔｉ０．８Ｆｅ１０．４Ｏ１９）磁粉的矫顽力、比饱和磁化强度、矩磁比等磁性质及其粒度的影响,结果表明,包硅使钡铁氧体（ＢａＣｏ０．８Ｔｉ０．８Ｆｅ１０．４Ｏ１９）磁粉的矫顽力和比饱和磁化强度略有下降,但钡铁氧体（ ＢａＣｏ０．８Ｔｉ０．８Ｆｅ１０．４Ｏ１９）磁粉的粒度也明显下降．这说明包硅可以提高磁粉的抗烧结能力,对于进一步细化钡铁氧体（ＢａＣｏ０．８Ｔｉ０．８Ｆｅ１０．４Ｏ１９）磁粉颗粒具有指导意义．     

Fe_xPt_(100-x)薄膜的磁性能研究

用直流磁控溅射方法和原位退火工艺在玻璃基片上制备了FexPt100-x纳米膜.研究发现Fe含量对FePt纳米膜的磁特性有很大的影响.矫顽力和△H随Fe含量的增加而增大.当x=48时,矫顽力Hc达到了1040 kA/m,样品出现很好的有序化L10织构;△H取得最大值,颗粒间相互作用最小.FexPt1-x薄膜的矩形比S随着x的增加而增大,x>46时S值接近1,在一定程度上表明了此时读出信号强度较大;开关场分布SFD的变化情况刚好与此相反,Fe48Pt52获得的SFD值近似等于0.8,说明转变位置波动弱,来自转变的信号噪音低.     

Dependence of Magnetic Properties and Microstructure of Ni81Fe19 Film on Base Vacuum and Sputtering Pressure

The Ni81Fe19/Ta films with different NiFe thickness were prepared at different base vacuums and sputtering pressures,The results of magnetic measurement and atomic force microscope(AFM),showed that the films prepared at higher base vacuum and lower sputtering pressure had larger ΔR/R,The reason should be that higher base vacuum and lower sputtering pressure introduce larger grain-size and lower surface roughnes,which will weaken the scattering of electrons,reduce the resistance R,and increase ΔR/R.     

Influence of O/Ar ratio on the properties of NiO thin film grown with the method of radio-frequency magnetron sputtering

In order to obtain high quality NiO thin film grown with the radio-frequency magnetron sputtering method, the influence of O/Ar ratio on the structure, band-gap, resistivity and optical transmittance of NiO thin films were studied. It was found that the obtained NiO thin film showed (111) preferred orientation and higher transparency in the visible region. With the increasing of O/Ar ratio from 1∶7 to 8∶2, the optical transmittance of NiO thin films decreased and the optical band-gap was between 3.4 eV and 3.7 eV, and the sheet resistivity decreased from 5.4×107 Ω/□ to 1.0 ×105 Ω/□. Our study shows that the properties of NiO thin films can be adjusted in a wide range by adjusting the O/Ar ratio in the sputtering process.     

NiOx激活PMS降解染料废水的研究（研究生论坛）

随着水处理行业的不断发展,对于传统的高级氧化技术（AOPs）也提出了更多新的要求,也开发了很多新的高性能催化剂用于高级氧化领域。为了探究NiOx在超声强化的条件下对单过硫酸盐（PMS）的催化性能,同时探究NiOx/PMS/US高级氧化体系对染料废水降解的优势,采用溶胶-凝胶法制备NiOx催化剂,酸性橙7（AO7）作为降解底物。探究发现：相比于NiOx/H2O2/US、NiOx/过硫酸盐（PDS）/US体系,NiOx/PMS/US体系具有更高的降解效率,且催化剂的煅烧温度、[氧化剂]:[氧化底物]、催化剂投量、超声功率都会对NiOx/PMS/US体系产生影响。结果表明：煅烧温度由200℃升至700℃后,AO7的降解率由95%降低至20%。[氧化剂]:[氧化底物]由20:1升至70:1,其降解率由77%提至95%,继续提高比例则会抑制降解。催化剂投量由120mg/L升至280mg/L,降解率提升不明显,在15分钟内都能达到95%的降解,但降解速率有所提升,继续提高催化剂投量其降解速率则没有明显的提高。超声功率由0W提至400W也会提高降解速率,但过高的超声功率对降解速率提高却不明显。此外,对催化剂复用以及对甲基橙（HIn）和活性艳蓝（KN-R）的降解证明NiOx/PMS/US体系具有一定的稳定性和普适性。NiOx的XRD图谱说明最佳煅烧温度下催化剂主要有NiO、Ni及无定型碳组成。NiOx是一种高效的催化剂,其良好的催化活性,稳定性和普适性,在高级氧化技术中可以发挥重要作用。当然其制备成本高和难以规模化生产成为了制约NiOx实现经济效益的主要因素,所以接下来的研究方向应为降低催化剂的制备成本并使其量产,最终让其进入应用领域。     

稀土元素铈离子掺杂对镍铬锌铁氧体电磁性能的影响

自蔓延燃烧法制备Ni0.4Cr0.4Zn0.2CexFe2-xO4(x=0,0.1)铁氧体,用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、振动样品磁强计(VSM)和矢量网络分析仪表征了铁氧体的结构形貌、磁性能及介电性能。结果表明:两种粉体粒径均在180nm左右,晶格常数为0.8364nm。由于Ce3+取代了部分Fe3+,导致Ni0.4Cr0.4Zn0.2Ce0.1Fe1.9O4的饱和磁化强度Ms从75.53emu/g增大到81.53emu/g,剩余磁化强度Mr由27.85emu/g增至32.58emu/g,但矫顽力Hc从481.56Oe降至453.42Oe,在8.0~20.0GHz频率范围内,Ni0.4Cr0.4Zn0.2Ce0.1Fe1.9O4的反射损耗明显高于Ni0.4Cr0.4Zn0.2Fe2O4,Ni0.4Cr0.4Zn0.2Fe2O4的反射损耗在-3.98d B~-5.11d B之间,Ni0.4Cr0.4Zn0.2Ce0.1Fe1.9O4的反射损耗在-5.18d B~-6.94d B之间。     

纳米氧化镍的制备及其电化学电容

通过金属碳酸盐、硝酸(氧化剂)和柠檬酸(燃料)的凝胶-燃烧方法合成了纳米氧化镍粉体。在柠檬酸与Ni2+的摩尔比为1.3:1,热处理温度为400℃的条件下,以1mol/LKOH水溶液为电解液对纳米NiOx制备的电极进行了循环伏安、充放电及电化学阻抗谱分析。分析结果表明纳米NiOx电极在KOH水溶液电解液中具有良好的赝电容特性,其平均比容量最大为78.8F/g,并具有良好的循环寿命。     

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。     

Effect of CaO doping on corrosion resistance of Cu/(NiFe_2O_4-10NiO) cermet inert anode for aluminum electrolysis

The CaO-doped Cu/(NiFe2O4-10NiO) cermet inert anodes were prepared by the cold isostatic pressing-sintering process, and their corrosion resistance to Na3AlF6-K3AlF6-Al2O3 melt was studied. The results show that the relative density of 5Cu/(NiFe2O4-10NiO) cermet sintered at 1 200 ℃ increases from 82.83% to 97.63% when 2% CaO (mass fraction) is added. During the electrolysis, the relative density of cermet inert anode descends owing to the chemical dissolution of additive CaO at ceramic grain boundary, which...     

The effect of interface roughness on the perpendicular exchange bias of NiO/CoPt/Pt stacking structure

An orthogonal coupling structure of Ni O/Co Pt/Pt/glass with perpendicular exchange bias effect has been prepared. The exchange bias is found to be strongly dependent on the interface roughness between Ni O and Co Pt layer. The conventional inverse proportionality of the exchange bias field with the ferromagnetic thickness is not applicable to this top-pinned stacking structure.Moreover, an anomalous ferromagnetic thickness dependence of blocking temperature is also observed. A simulation on the basis of a spin configuration model with defects at the interface agrees well with the experimental observations. These findings suggest considerable contribution of the interface roughness to the perpendicular exchange bias.     

Fe3B添加量对Nd-Fe-B快淬薄带结构与磁性能的影响

通过在Nd2Fe14B合金中按Fe3B原子比同时添加Fe与B,研究了Nd15Fe77B8、Nd9Fe81B10、Nd4.5Fe77.0B18.5 3种合金薄带的结构与磁性能.试验发现,40 m/s的快淬速度使三种合金薄带中形成了较多的非晶相,而且随着合金中Fe3B添加量的增加,薄带的非晶形成能力增强、α-Fe与Fe23B6含量增加、Nd2Fe14B含量减少,磁性能单调降低.经680℃保温10 min退火处理后,3种薄带中的非晶相明显减少,Fe3B相消失,.α-Fe与Fe23B6含量随Fe3B添加量的增加而增加.其中,薄带中Nd2Fe14B晶粒约50 ～ 100 nm,而α-Fe晶粒一般小于50 nm.Nd15Fe77B8退火薄带更多地表现为单硬磁相特征;Nd9Fe81B10退火薄带中形成了α-Fe/Nd2Fe14B/Fe23B6三相交换耦合微结构,剩磁比达到了0.612,并获得最大的剩磁58.3 A· m2/kg;而Nd4.5Fe77.0B18.5薄带中Fe23B6与α-Fe含量太高,矫顽力太低而使剩磁增强效应不明显.     

Preparation and properties of 4.25Cu-0.75Ni/NiFe_2O_4 cermet

1INTRODUCTION NiFe2O4cermets,whichareexpectedtobe usedastheinertanodesforaluminumelectrolysis, havelowcorrosionandoxidation,goodelectricalconductivityandhighthermalshockresistance[15]. Nickelferritespinelformsacorrosion resistant networkthatcontainstheelectricallyconductivecopper basedmetallicphase.Especially,Gregget al[6]foundacermetofNiFe2O4 18%NiO 17%Cu (massfraction),whichshowedfavorablecorrosion andconductivitypropertiesasinertanodesinsmalllaboratorycells.However,itwasalsoshowedth…     

自旋为1/2的亚铁磁棱型X-Y链的内能

利用不变本征算符法计算低温下自旋为1/2的一维亚铁磁棱型X-Y链系统的元激发谱,并讨论在此系统中不同特殊情形下的元激发能量.推导出体系的3个临界磁场强度(H C1,H C2,H Peak).讨论当外磁场HH C1或HH C2时,体系出现能隙;当H C1HH C2时体系不出现能隙的物理机制.体系的内能随外加磁场的增加逐渐减少,随温度的升高逐渐增大.绝对零度下,在高外磁场区二聚体分子内电子自旋平行排列的铁磁交换作用能J F与二聚体与单基体分子间电子自旋反平行排列的反铁磁交换作用能J AF之比(-J F/J AF)对体系的内能几乎无影响.但在有限温度,大外磁场下时,曲线重合出现分裂迹象.