Magnetic Properties of Permalloy/Cu-Au Multilayers

The interlayer exchange coupling and GMR effect of (permalloy/Cu _x Au_1-x )30 (Py = Ni₈₃Fe₁₇; 0.29x0.75) sputtered multilayers (MLs) were investigated. The strength of the antiferromagnetic (AF) interlayer coupling J _AF was determined from M(H) and/or R(H) curves. GMR effect and AF coupling was found in entire investigated concentration range of Cu _x Au_1-x . For x<0.65 the J _AF values at the first maximum of AF coupling (1.3t _Cu-Au1.6 nm) were smaller than 3×10^-6 J/m² and for x>0.65 J _AF increased to a value characteristic of Py/Cu MLs (J _AF10^-5 J/m²). The second maximum of AF coupling (J _AF10^-7 J/m²) was only found for x0.75 at t _Cu-Au2.6 nm.     

Influence of the Interfaces on Magnetic Properties of Fe/Ag and Fe/Cu Multilayers Prepared by Sputtering

Hyperfine Interactions - Dependence of magnetic behavior of ultrathin Fe layers on the width of the interfaces was investigated by using dc-magnetron sputtering to grow (Fe(110)/Ag(111))...     

半花菁LB多层膜的光致各向异性研究

用光学线性和非线性方法研究了Ｙ型半花菁／花生酸交替ＬＢ多层膜的光致光学各向异性。在纳秒紫外偏振脉冲激光照射下，ＬＢ多层膜中半花菁分子发色团长轴向紫外光偏振方向重新取向。加热可以使ＬＢ多层膜平面内各向异性消失及Ｈ－聚集体分解。     

MgO/Pt界面对增强Co/Ni多层膜垂直磁各向异性及热稳定性的研究

采用直流磁控溅射法在玻璃基片上制备了Pt底层和MgO/Pt双底层的Co/Ni多层膜样品, 通过反常霍尔效应研究了不同MgO厚度和退火温度对样品垂直磁各向异性(perpendicular magnetic anisotropy, PMA)的影响. 随着底层中MgO厚度的逐渐增加, 样品的矫顽力也随之增强, 霍尔电阻变化不大; 对样品进行退火处理后发现, 单纯Pt底层的Co/Ni多层膜随着退火温度的升高, 霍尔电阻逐渐降低, 矫顽力则迅速降低, 热稳定性较差; 而当MgO/Pt双底层的样品在200 ℃退火后矫顽力大幅增加, 霍尔电阻略微有所减小, 更高的退火温度使得Co和Ni合金化, 导致多层膜的PMA特征减弱.     

Effect of Interface Roughness on Perpendicular Magnetic Anisotropy of Fe/Tb Multilayers

Fe/Tb multilayers have been prepared which exhibit significant perpendicular magnetic anisotropy (PMA) even at RT. The effect of systematic variation in the interface roughness on PMA has been studied in these multilayers which were deposited simultaneously on a set of float glass substrates prepared with varying root mean square surface roughness. The amount of intermixing at the interfaces and uncorrelated part of the interface roughness of different multilayers remain similar, thus allowing one to separate out the effect of the correlated interface roughness only. X-ray reflectivity and conversion electron Mössbauer spectroscopy and SQUID magnetometry was used to characterise the systems. PMA was found to depend weakly on the correlated interface roughness.     

多层膜［Co85Cr15/Pt］20的磁性、垂直磁记录特性和微结构的关系

采用磁控溅射法制备了性能优良的以Pt为缓冲层的［Co85₈₅Cr15_{15/Pt］2020 多层膜，研究了溅射气压对［Co8585Cr1515/Pt］2020多层膜微结构和磁性的 影响.研究结果表明，Ar溅射气压对［Co8585Cr1515/Pt］2020多层膜的微结构 、垂直磁各向异性和矫顽力有重要的影响 关键词： 溅射气压 多层膜 垂直磁各向异性 有效磁各向异性常数}     

具有条纹磁畴结构的NiFe薄膜的制备与磁各向异性研究

具有条纹磁畴结构的磁性薄膜表现出面内转动磁各向异性,对于解决高频电子器件的方向性问题起着至关重要的作用.本文采用射频磁控溅射的方法,研究了NiFe薄膜的厚度、溅射功率密度、溅射气压等制备工艺参数对条纹磁畴结构、面内静态磁各向异性、面内转动磁各向异性、垂直磁各向异性的影响规律.研究发现,在功率密度15.6 W/cm~2与溅射气压2 mTorr(1 Torr=1.33322×102Pa)下生长的NiFe薄膜,表现出条纹磁畴的临界厚度在250 nm到300 nm之间.厚度为300 nm的薄膜比250 nm薄膜的垂直磁各向异性场增大近一倍,从而磁矩偏离膜面形成条纹磁畴结构,并表现出面内转动磁各向异性.高溅射功率密度可以降低薄膜出现条纹磁畴的临界厚度.在相同功率密度15.6 W/cm~2下生长300 nm的NiFe薄膜,随着溅射气压由2 mTorr增大到9 mTorr,NiFe薄膜的垂直磁各向异性场逐渐由1247.8 Oe(1 Oe=79.5775 A/m)增大到3248.0 Oe,面内转动磁各向异性场由72.5 Oe增大到141.9 Oe,条纹磁畴周期从0.53μm单调减小到0.24μm.NiFe薄膜的断面结构表明柱状晶的形成是表现出条纹磁畴结构的本质原因,高功率密度下低溅射气压有利于柱状晶结构的形成,表现出规整的条纹磁畴结构,高溅射气压会导致柱状晶纤细化,面内转动磁各向异性与面外垂直磁各向异性增强,条纹磁畴结构变得混乱.     

Co/Ni多层膜垂直磁各向异性的研究

采用直流磁控溅射法在玻璃基片上制备了Pt底层的Co/Ni多层膜样品, 对影响样品垂直磁各向异性的各因素进行了调制, 通过样品的反常霍尔效应系统的研究了Co/Ni多层膜的垂直磁各向异性. 结果表明, 多层膜中各层的厚度及周期数对样品的反常霍尔效应和磁性有重要的影响. 通过对多层膜各个参数的调制优化, 最终获得了具有良好的垂直磁各向异性的Co/Ni多层膜最佳样品Pt(2.0)/Co(0.2)/Ni(0.4)/Co(0.2)/Pt(2.0), 经计算, 该样品的各向异性常数K_eff 达到了3.6×10⁵ J/m³, 说明样品具备良好的垂直磁各向异性. 最佳样品磁性层厚度仅为0.8 nm, 样品总厚度在5 nm以内, 可更为深入的研究其与元件的集成性.     

Magnetic Properties of Spin-1/2 Quantum Heisenberg Ferromagnet with Spatially Anisotropy

The spin-1/2 quantum Heisenberg ferromagnet with anisotropic spin exchange interactions in three dimensions are investigated by means of the Green's function method. In the Tyablikov approximation, the correlation functions, the magnetization, and the susceptibilities are computed. The magnetic properties of this model are found to be dependent of anisotropy.     

Quantum Theory for Interfacial Roughness and Angle Dependence of Giant Magnetoresistance in Magnetic Multilayers

The giant magnetoresistance(GMR)in magnetic multilayers with current in the plane of the layers is studied by using the quantum-statistical Green‘s function approach,in which the effects of the interfacial roughness and magnetization configuration on the GMR are included,It is shown that the maximal GMR first increses and then decreases with increasing interfacial roughness,exhibiting a peak at an optimum value of interfacial roughness.An approximately linear dependence of GMR on sin^2(θ/2)is obtained,where θ is the angle between magnetizations of the two successive ferromagnetic layers,FUrthermore,the maximal GMR is found to increase with increasing the number of bilayers.     

Exchange coupling effects in NiO/Co and NiO/permalloy bilayers

NiO/Co and NiO/Ni₈₀Fe₂₀ bilayers were prepared at 293 onto SiO₂(1 0 1)/Si(1 1 1) and glass substrates using UHV (5×10⁻¹⁰ mbar) RF/DC magnetron sputtering. Results on magnetic measurements showed that the exchange biasing and coercive fields are inversely proportional to the Co and Ni₈₀Fe₂₀ (Py) layer thickness down to 2 nm. A maximal RT coupling energy for the NiO–Co and NiO–Py interface was estimated as 0.04 and 0.03 mJ/m² for the samples prepared onto SiO₂(1 0 1)/Si(1 1 1) substrates.     

直流磁控溅射Si和玻璃衬底Fe/Co多层膜的磁性能比较

对直流磁控溅射Si和玻璃衬底［Co_t/Fe_3t］₅(t=2, 3, 4, 5nm)多层膜的磁性能进行了比较.对于t相同但衬底不同的样品,实验发现饱和磁化强度相差很小,但是矫顽力却相差很大.对矫顽力差异的理论分析表明,多层膜的粗糙度和畴壁类型是引起这种差异的主要原因. 关键词： Fe/Co多层膜 磁性能 矫顽力     

直流磁控溅射Si和玻璃衬底Fe/Co多层膜的磁性能比较

对直流磁控溅射Si和玻璃衬底［Co_t/Fe_3t］₅(t=2, 3, 4, 5nm)多层膜的磁性能进行了比较.对于t相同但衬底不同的样品，实验发现饱和磁化强度相差很小，但是矫顽力却相差很大.对矫顽力差异的理论分析表明，多层膜的粗糙度和畴壁类型是引起这种差异的主要原因.     

Fe/Nb多层膜中离子辐照效应研究(英文)

〗采用磁控溅射技术在Si衬底上沉积Si/\[Fe(10 nm)/Nb(4 nm)/Fe(4 nm)/Nb(4 nm)\]2/ \[Fe(4 nm)/Nb(4 nm)\]4多层膜。 用2 MeV的 Xe离子在室温下辐照多层膜。采用俄歇深度剖析、X射线衍射和振动样品磁强计分析辐照引起的多层膜元素分布、 结构及磁性变化。AES深度剖析谱显示当辐照注量达到1.0×1014 ions/cm2时, 多层膜界面两侧元素开始混合; 当辐照注量达到2.0×1016ions/cm2时, 多层膜层状结构消失, Fe层与Nb层几乎完全混合。XRD谱显示, 当辐照注量达到1.0×1014ions/cm2时, Nb的衍射峰和Fe的各衍射峰的峰位相对于标准卡片向小角方向偏移, 这说明辐照引起Nb基和Fe基FeNb固溶体相的形成;当辐照注量大于1.0×1015 ions/cm2时, 辐照引起非晶相的出现。 VSM测试显示,多层膜的磁性随着结构的变化而变化。 在此实验基础上, 对离子辐照引起界面混合现象的机理进行了探讨。The behavior of the metallic multilayers of Si/\[Fe(10 nm)/Nb(4 nm)/Fe(4 nm)/ Nb(4 nm)\]2/\[Fe(4 nm)/Nb(4 nm)\]4 under 2 MeV Xe ion irradiation has been investigated by depth profile analysis of Auger electron spectroscopy,X ray diffraction and vibrating sample magnetometer. The obtained experimental results show that the inter mixing between Fe and Nb layers occurs in the 1.0×1014 ions/cm2 irradiated multilayer sample which results in the formation of Nb based and Fe based FeNb solid solution. For the samples irradiated to fluence larger than 1.0×1014 ions/cm2, amorphisation is observed, and moreover, the layered structure of the multilayer samples is broken up completely for the samples under 1.0×1016 or 2.0×1016 ions/cm2 irradiation. Vibrating sample magnetometer measurement also reveals that the magnetization of the samples changes with the evolution of the structure of multilayers. Possible mechanism of the modification in Fe/Nb multilayers induced by Xe ion irradiation is briefly discussed.     

PdMn/Co多层膜的磁性和磁光特性研究

用磁控溅射法制备了不同Mn含量的PdMn/Co磁性多层膜，通过x射线衍射对该多层膜系列进行结构分析；测定了不同Mn含量系列样品的磁滞回线、垂直各向异性及磁力显微镜图，分析了饱和磁化强度、磁畴和垂直各向异性变化的原因；通过测定该多层膜体系的克尔谱，简要分析了一定波长下克尔角随Mn含量增加而变化的物理机制. 关键词： 多层膜 磁性 磁光     

Tunable interface anisotropy in a Pt/Co_(1-x)Fe_x/Pt multilayer

Interfacial magnetic anisotropy in a Pt/Co1-xFex /Pt multilayer is tuned by doping iron atoms into the cobalt layer.The perpendicular magnetic anisotropy and out-of-plane coercivity are found to decrease with increasing x.For a specific x,the out-of-plane coercivity acquires a maximal value as a function of the thickness of the CoFe layer.At low temperature,the coercivity is enhanced.Small coercivity but reasonably large perpendicular magnetic anisotropy can be obtained by controlling the x and CoFe layer thickness.     

Magnetic properties of Fe/ZnSe/Fe trilayers

The magnetic properties of Fe/Zn/Fe trilayers have been studied by ferromagnetic resonance and magnetization measurements. These measurements have been used to investigate the magnetic anisotropy of the iron layers and the magnetic coupling across the semiconductor spacer. The angular dependence of the resonance spectra has been measured in-plane and out-of-plane in order to deduce magnetic anisotropy constants of the samples. Experimental data were fitted by using an energy-density expression that includes bulk cubic anisotropy, growth-induced uniaxial in-plane anisotropy and perpendicular-surface anisotropy terms. A small ferromagnetic coupling is observed in the trilayers with spacer thickness up to .     

Anisotropic interface magnetoresistances in Pt(111)/Co n /Pt(111)

It is shown in terms of a fully relativistic spin-polarized ab initio-type approach that in Pt/Co/Pt trilayers two types of anisotropic magnetoresistance (AMR) have to be distinguished: an in-plane and an out-of-plane AMR. The obtained results, namely the magnetic field dependence as well as the thickness dependence of both AMR types are in very good agreement with a very recent experimental study, in which the in-plane as well as the out-of-plane AMR was reported for this system. The difference between the two types of AMR is visualized in terms of layer-resolved resistivities. In particular, it is confirmed that the anisotropic interface magnetoresistance (AIMR) introduced in the recent publication mainly originates in the vicinity of the Co/Pt interfaces.