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     

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     

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。     

Co/Pt多层膜X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,解释多层膜小角衍射主峰之间出现次峰的现象,并确立了次峰个数与膜周期数之间的关系。     

Co/Pt多层膜的调制结构对磁光性能的影响

研究了Ｃｏ／Ｐｔ多层膜中,Ｃｏ层厚度,Ｃｏ、Ｐｔ含量比,溅射温度对多层膜磁光性能的影响。研究发现Ｃｏ层厚度及Ｃｏ、Ｐｔ含量比对Ｃｏ／ｐｔ多层膜的磁光性能起决定性影响。当ｔＣｏ〈０．４ｎｍ,ｔＣｏ／ｔＰｔ＝１／２时。可获得较好的综合磁光性能;适当提高溅射时基体的温度,可改善多层膜的结晶性并获得较好的调制周期结构,最终改善其磁光性能。     

Co／C多层膜的结构稳定性

用Ｘ射线衍射、透射电镜、Ｒａｍａｎ光谱、Ｘ射线光电子谱等测量方法研究了用对向靶溅射法制备的Ｃｏ／Ｃ多层膜的结构热稳定性．退火Ｃｏ／Ｃ多层膜的结构变化包括周期膨胀、非晶Ｃｏ层结晶、掠入射反射率变化以及化合物的形成．４００℃退火，周期膨胀主要是由于非晶碳层的石墨化．Ｃｏ／Ｃ系统的相分离造成掠入射反射率增强，可解释为Ｃｏ／Ｃ系统的正的混合焓．５００℃退火，Ｃｏ层的结晶和集聚导致了周期的异常膨胀和反射率的降低．此时界面处形成了少量的碳化物．     

Pt／Co／Pt／Ni多层膜的结构与磁性

为了改变Pt/Co多层膜的磁光特性与磁性,插入与第三元素层是有效途径之一。我们研究表明,插入Ni可导致居里温度Tc的下降。所插的层最佳厚度为0．3－1．0nm,X射线衍射实验表明,插入Ni层后的样品具有良好的成层结构。Pt（111）峰与Co(111）峰的位置分别比纯Pt/Co相应的峰略向左移和向右移,这证明面间距分别是增大和缩小。磁性测定,由于Ni层的插入磁光克尔角θk略有增高,剩磁比与矫顽力的性能更好。     

稀土元素Gd对Co/Pt多层膜居里温度的影响

采用镶嵌靶法制备添加稀土元素Gd的Co／Pt多层膜，以θk＝0和铁磁性消失的温度表征居里温度(Tc)。研究结果表明：添加适量Gd于Co／Pt多层膜中，其Tc＜200℃；在本工作研究的成分范围内，Tc随Gd含量增加而降低。运用分子场理论讨论了Tc与交换作用的关系，并根据s—f电子交换模型探讨了添加稀土元素降低Co/Pt多层膜Tc的机理。     

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/Cu/Co纳米多层膜的铁磁耦合效应

采用洛仑兹电子显微镜研究了磁控溅射沉积制备的Cu(20 nm)/Co/Cu/Co纳米多层膜磁畴结构随铁磁层间耦合效应的变化. Cu中间层厚度较薄时, 由于铁磁层之间的耦合作用, 纳米多层膜为垂直易磁化, 磁畴为磁泡结构, 磁泡的平均直径随Cu中间层厚度的增加而减小, 多层膜矫顽力呈减小趋势. 当Cu中间层厚度大于3 nm时, 铁磁层之间的耦合作用减弱, 纳米多层膜为面内易磁化, 磁泡结构的磁畴消失, 全部为具有波纹状的接近180°畴壁的磁畴结构.     

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.     

离子束溅射制备Pt/C催化电极材料的结构和电化学性能

采用离子束溅射技术制Ｐｔ／Ｃ催化电极,降低了电极耗铂量至０．１９ｍｇ／ｃｍ＾２,电极具有良好的电化学性能。研究了在不同碳质载体材料上用不同沉积条件制备的Ｐｔ／Ｃ电极的电化学性能。     

磁控溅射沉积Al/AlN纳米多层膜的摩擦学性能

纳米多层膜因具有优异的力学性能与抗摩擦磨损性能使其在摩擦学领域具有重要的应用价值。采用磁控溅射沉积法制备了Al、AlN单层薄膜与Al/AlN纳米多层膜,探讨了纳米多层化对薄膜的力学性能和摩擦学性能的影响。采用纳米压痕仪和摩擦磨损试验机测量评价薄膜的纳米硬度和摩擦学性能。结果表明:Al/AlN纳米多层膜具有良好的周期调制结构,多层膜中的大量界面能显著提高薄膜的力学性能与摩擦学性能。多层膜的硬度为8.8GPa,高于采用混合法则计算出的硬度值6.6GPa;多层膜具有软质Al层和硬质AlN层的交替结构,在摩擦过程中,硬质AlN层可以起到良好的承载作用,软质层可以起到良好的减摩作用。相对于Al单层薄膜或AlN单层薄膜,Al/AlN纳米多层膜具有较低的摩擦因数(0.15)和优异的抗磨损性能。     

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.     

Co/Cr/Pd多层膜的磁性及其准确性

研究了测量程序对不同Cr层厚度的Co／Cr／Pd多层膜磁性的影响，分析了反磁化机理在不同测量程序中对磁性准确性的影响。