离子束溅射制备Co／Pt多层膜的磁性研究

室温下采用ＶＳＭ测定了离子束溅射（ＩＢＳＤ）技术制备的Ｃｏ／Ｐｔ多层膜垂直方向的Ｍ－Ｈ回线。研究结果表明：Ｃｏ／Ｐｔ多层膜中单位体积Ｃｏ的饱和磁化强度ＭｓＣｏ小于块状Ｃｏ的饱和磁化强度;Ｃｏ／Ｐｔ多层膜的饱和磁化强度（Ｍｓ）与厚度有关：随Ｃｏ层厚度ｔＰｔ和多层膜总厚度ｔｆ的增加而增大,随Ｐｔ层厚度ｔｐｔ的增加而减小;外推结果表明当ｔＣｏ小于一个原子层厚（≈０２５ｎｍ）时,室温下Ｃｏ／Ｐｔ多层膜的饱和磁化强度为零,呈顺磁性     

离子束溅射制备Co／Pt多层膜的结构

采用高角Ｘ射线衍射（ＨＸＲＤ）和ＴＥＭ研究用离子束溅射（ＩＢＳＤ）技术制备的Ｃｏ／Ｐｔ多层膜的晶体结构和显微组织形貌，结果表明：Ｃｏ／Ｐｔ多层膜的晶体结构与Ｃｏ、Ｐｔ层厚度ｔＣｏ、ｔＰｔ密切相关。当ｔＣｏ＜ｔＰｔ＜２１０时，Ｃｏ、Ｐｔ层为共格ｆｃｃ结构，随ｔＣｏ、ｔＰｔ增加，逐渐向非共格关系转变，同时，Ｐｔ、Ｃｏ层晶格发生了严重畸变。ＴＥＭ发现Ｃｏ／Ｐｔ多层膜的组织形貌明显受基底影响，与沉积在Ｓｉ基底表面上的Ｃｏ／Ｐｔ多层膜相比，沉积在ＮａＣｌ上的Ｃｏ／Ｐｔ多层膜的晶粒出现择优取向且呈条纹状分布，晶粒明显粗化     

Co/Pt多层膜的结构和饱和磁化强度

采用离子束溅射技术制备Ｃｏ／Ｐｔ多层膜,用ＲＢＳ、小角ＸＲＤ和断面ＴＥＭ研究了多层膜的周期性调制结构,用ＶＳＭ研究了磁性层Ｃｏ和顺磁性层Ｐｔ的厚度变化对饱和磁化强度的影响。结果表明,多层膜具有良好的周期性层状结构,和设计值一致。样品的饱和磁化强度（Ｍｓ）随Ｃｏ层厚度增加而增大,随Ｐｔ层的厚度增大而减小。当Ｃｏ层和Ｐｔ层的厚度比一定时,样品的饱和磁化强度不受周期数的影响,符合Ｍｓ＝ＭｃｏｔＣｏ／Ｄ模     

TbFeCo/(Pt,Pd,NdCo)多层膜的磁光特性

为了提高记录密度而力求光磁记录的短波长化,这就要求在短波长区域磁光效果大的材料,进一步考虑到磁特性,力求其成分和制取条件的最佳化。现在常用的非晶态ＴｂＦｅＣｏ膜,为了减小其在短波长区域的Ｋｅｒｒ回转角,就必须通过添加其它元素来提高它在短波长区域的磁光效果。为了研究通过添加Ｐｔ、Ｐｄ和ＮｄＣｏ而使得ＴｂＦｅＣｏ能在短波长区域使用的可能性,而制备了ＴｂＦｅＣｏ／（Ｐｔ,Ｐｄ,ＮｄＣｏ）多层膜和ＮｄＴｂＦｅＣｏ合金膜。研究了添加元素、Ｐｔ、Ｐｄ、ＮｄＣｏ各层厚度对多层膜的磁性和磁光特性的影响。研究用的…     

Co／Pt多层膜磁光记录介质材料研究进展

叙述Ｃｏ／Ｐｔ多层膜的磁光性能，以及其尺寸、制备技术、工艺条件、结构等因素对磁光性能的影响，并介绍上述材料的研究进展。     

退火[Co＼Cu]多层膜的固相反应与磁性

用双对向靶溅射方法制备了两种成分的「Ｃｏ（１．２ｎｍ）／Ｃｕ（ｔＣｕ）」（ｔＣｕ＝１．０ｎｍ，３．４ｎｍ）纳米多层膜。分别用ＴＥＭ和ＴＧ方法研究了「Ｃｏ／Ｃｕ」多层膜结构和磁怀随温度的变化。结果表明：ｔＣｕ＝１．０ｎｍ的多层样品出现了两个磁性转变点，这是因为样品中存在的两种磁性物质。ＴＥＭ分析结果证明这两种铁磁相为ｈｃｐＣｏ－Ｃｕ固溶体。     

Co／Ti非晶多层膜晶化过程中结构及磁性的变化

利用双对向靶溅射方法在室温下制备Ｃｏ／Ｔｉ非晶多层膜，并采用原位退火透射电镜和原位热重法，观测了Ｃｏ／Ｔｉ多层膜结构与磁性随温度的变化，结果表明：退火温度ｔａ为４００℃时，薄膜开始晶化，Ｃｏ，Ｔｉ颗粒析出并粗化；ｔａ＞６００℃时，具有铁磁性的Ｃｏ单质完全消失，全部转化为Ｃｏ２Ｔｉ相．热磁测量在３９０及５２０℃附近出现了两个明显的磁性转变峰，与薄膜结构变化对应．适当温度（４００—５２０℃）的退火可获得高饱和磁化强度的Ｃｏ－Ｔｉ颗粒膜．     

Co—Nb／Cr磁性多层膜的振荡耦合

Ｃｏ－Ｎｂ－Ｃｒ磁性多层膜由高频溅射方法制得,由振动样品磁强计测量样品的磁性能。在２．６７Ｐａ溅射氩气压下,发现样品随Ｃｆ层厚度增加,铁磁层间出现铁磁性和反铁磁性的耦合振荡,饱和磁化强度Ｍｓ基本保持不变,而在０．６７Ｐａ溅射氩气压下,样品的饱和磁化强度Ｍｓ发生了振荡,这可能与春铁磁层中顺磁分量振荡变化有关。     

Co／Pt多层膜D射线小角衍射分析

对Ｃｏ／Ｐｔ多层膜进行Ｘ射线小角衍射分析，测量出多层膜的周期厚度和解释多层膜小角衍射主峰之间出现次峰的现象，并确立次峰个数与膜周期数之间的关系。     

Tb／Co成分调制膜的磁,磁光性能和热稳定性

用直流磁控溅射制备了Ｔｂ／Ｃｏ成分调制膜，膜调制结构的形成与靶的溅射速率和衬底转速密切有关。对不同周期的Ｔｂ／Ｃｏ膜的极向Ｋｅｒｒ膜滞间回线进行了测量，结果表明：当Ｔｂ／Ｃｏ膜的周期较小时，薄膜具有垂直方向的磁各向异性，较大的矫顽力和较大的磁光效应；当Ｔｂ／Ｃｏ膜的周期较大时，上述性能变差。     

Magnetization and coercivity in Co/Pt multilayers with constant total Co layer thickness

Co/Pt multilayers with perpendicular anisotropy were deposited using a dc magnetron sputtering system under high vacuum. Magnetization process was investigated by the measurement of magnetic components parallel and perpendicular to the applied field. A dependence of the coercivity of Co/Pt multilayers on the Co layer thickness was reported, in which the total thickness of Co layers kept constant. It is observed that the coercivity increases with the increment of Co layer thickness. For the samples with the same Co layer thickness while different total Co layer thickness, the coercivity first increases and then decreases with the increase of the total thickness of Co layers. This effect could be attributed to the competition between the reduction of HC related to incoherent reversal and the step-up of HC contributed by the magnetic polarization of Pt atoms at the interface of Co and Pt layers during magnetization reversal. The results show that the change of the coercivity is strongly related to the Co layer thickness, but not the total thickness of Co layers. The dependence of the coercivity on the angle between an applied field and the easy axis shows that the nucleation mode is dominant in magnetization reversal process of the samples.     

[Co／Ti],[Co／Cu（Ni）]多层膜的结构与磁性

用双对向靶溅射方法制备了具有非晶磁性的「Ｃｏ／Ｔｉ」３０，「Ｃｏ／Ｃｕ（Ｎｉ）３０」两组多层膜，分别用Ｘ射线衍射，透射电镜和振动样品磁强计做了结构和磁性测量，在以非晶Ｃｏ和Ｃｉｕ－Ｎｉ合金构成的「Ｃｏ／Ｃｕ（Ｎｉ）」多层膜中，发现饱和磁化强度Ｍｓ随非磁性层厚度ｄｓ的增国发生振荡变化；在以非晶Ｃｏ和Ｔｉ构成的「Ｃｏ／Ｔｉ」多层膜中，ＭＳ和则随ｄｓ的增加而减小。     

反应磁控溅射TiN/AlON纳米多层膜的微结构与显微硬度

采用Ti靶和Al2O3靶在Ar、 N2混合气氛中进行反应磁控溅射的方法,制备了一系列不同AlON层厚度的TiN/AlON纳米多层膜,利用EDS、XRD、HRTEM和微力学探针研究了AlON的形成条件以及AlON调制层厚的改变对多层膜生长方式和显微硬度的影响.结果表明,在Ar、N2混合气氛中对Al2O3进行溅射,N原子会部分取代Al2O3中的O原子,形成非晶态的AlON化合物.在TiN/AION纳米多层膜中,由于TiN晶体层的模板效应,AlON层在厚度小于0.6 nm时被强制晶化并与TiN形成共格外延生长结构,多层膜显示出最高硬度达40.5 Gpa的超硬效应;进一步增加AlON的层厚,其生长模式由晶态向非晶态转变,破坏了多层膜的共格外延生长结构,多层膜的硬度随之降低.     

The effect of multilayer structure on magnetic properties of FePt thin films

The Fe/Pt multilayer films with different structures were deposited by RF magnetron sputtering on glass substrates, and the L1₀-FePt films were obtained after theas-deposited samples were subjected to vacuum annealing at various temperatures. Results show that the Fe/Pt multilayer structure can effectively reduce the ordering temperature of FePt film, and the in-plane coercivity of [Fe (5.2 nm)/Pt (5.2 nm)]₇ multilayers can reach 161.2 kA/m after annealed at 350 ℃ for 30 min. When Fe and Pt layer thickness is equal, the coercivity of the film is the largest. On the other hand, the different Fe-Pt crystalline phases such as Fe₃Pt and FePt₃ phases are formed after annealing when the thickness ratio of Fe/Pt deviates from 1 after annealing. When Fe and Pt have the same thickness, the thinner single layer gets the lower ordering temperature and the larger coercivity.     

STRUCTURE, MAGNETISM AND MAGNETORESISTANCE OF ANNEALED Co/Cu DISCONTINUOUS MULTILAYERS

1.IntroductionGiantmagnetoresistance(GMR)inmultilayprsandgranularfilmshasattractedmuchattentionforitsimportanceintheoriesandapplications.Recently,inordertoredlicethesaturationmagneticfieldofGMRl'orlow--fieldsensorapplications,someattemptshavebeenmadetoprepareintermediatesystemsbetweenmultilayersandgranularfiimsfl--6],suchasmultilayerswith1lltrathinandthereforediscontinuousmagneticlayersll,2]orannealedmagneticmultilayers[3--6].However,theverythinmagneticlayersbecomesuperparamagneticatroomtemp…     

Co/Pt multilayer-based pseudo spin valves with perpendicular magnetic anisotropy

Pseudo spin valves(SVs) exhibiting perpendicular magnetic anisotropy were prepared by magnetron sputtering. Magnetization measurements of the Co/Pt multilayers were performed to select the reference and free layers. The selection criteria are square magnetic hysteresis loops, weaker current shunting effect, and proper coercivity. The optimal reference layer and free layer are Pt(5.0 nm)/[Co(0.4 nm)/Pt(0.6 nm)]3/Co(0.4 nm)/Cu(3.0 nm)and Cu(3.0 nm)/[Co(0.4 nm)/Pt(1.5 nm)]4, respectively.The resulting pseudo SV exhibits two well-separated hysteresis loops when the field is applied perpendicular to the film plane. The minor hysteresis loop corresponding to the free layer shifts toward negative direction of the magnetic field axis, indicating ferromagnetic interlayer exchange coupling between the two magnetic layers. The coupling also enhances the coercivity(HC) of both layers. The perpendicular giant magnetoresistance(GMR) of 2.7 % is achieved with current in plane measurement. The GMR first increases when Pt seed layer is thickened, reaches a maximum of 3.0 % at 4 nm and then decreases with the further increase of thickness. But thicker Cu spacer layer always lowers the GMR of the SV.     

Effect of Ti layer thickness on microstructure and magnetic properties of Ti/Co/Ti films

TiCoTi granular films were prepared by DC facing-target magnetron sputtering system onto glass substrates and subsequently in situ annealing in vacuum. Structural of Ti ( t nm)/Co (40 nm)/Ti ( t nm) films were investigated in detail, which shows that the majority Co nanograins are formed as the hexagonal-close-packed (HCP) structure. Vibrating sample magnetometer (VSM) and scanning probe microscope (SPM) were applied to study the magnetic properties, morphologies and domain structures of these samples. It has been found that the structure and magnetic properties of the Ti/Co/Ti films depend strongly on the Ti layer thickness. The out-of-plane coercivities ( Hc) of the film is maximum about 78.8 kA·m-1 when t =5 nm with annealing at 300 ℃; the distributing of grains of the sample is uniformity; and the average size of particles is about 13 nm. The obtained results suggest that this system is perpendicular anisotropy and might be applicable to perpendicular magnetic recording media.     

Inter-granular exchange coupling and magnetic anisotropy of Ta/Ru/Co-23 at%Pt perpendicular thin films with different Ru underlayer thicknesses

In the present work, a series of Ta/Ru/Co-23 at%Pt thin films with varied Ru underlayer thicknesses were fabricated by magnetron sputtering. All of the films show c-axis preferred orientation perpendicular to the film surface. The drop of c/a ratio and lattice expansion of Co–Pt layer with the increase in Ru underlayer thickness was revealed by X-ray diffraction(XRD). The coercivity of the Ta/Ru/Co–Pt thin films increases drastically with Ru underlayer thickness increasing, due to the enhancement of effective magneto-crystalline anisotropy constant and exchange decoupling of magnetic nano-grains. The enhancement of effective magneto-crystalline anisotropy constant is ascribed to the lattice deformation of Co–Pt layer by mismatching the Ru layer and Co–Pt surface.Moreover, the exchange decoupling of magnetic nanograins is attributed to the further isolation of magnetic nano-grains.     

Micro-structure, nano-property and nano-tribological behaviour of the permalloy/copper multilayers

The micro-structure, nano-mechanical behaviour of permalloy/copper magnetic multilayers with various permalloy layer thickness were investigated using scanning probe microscope, X-ray diffraction and nano-mechanical measuring system. Experimental results show that both copper and permalloy layers of these multilayers grow as a meta-stable phase. The multilayers are a good combination of toughness and hardness in the nano-mechanical properties compared with permalloy and copper single layer films. The permalloy layer thickness has a great effect on the micro-tribological behaviour of the permalloy/copper multilayers. When the permalloy layer thickness is reduced to ≤ 1.6 nm, the multilayers exhibit a large critical load, a small scratch width and a low residual scratch depth. When the permalloy layer thickness is reduced from 2.8 nm to 1.2 nm, the surface topography of the multilayers becomes smooth and the particle size decreases from about 120 nm to 25 nm, which will be beneficial to the applications that require a smooth surface.