钡铁氧体粒子反磁化研究

提出了钡铁氧体粒子反磁化的多扁椭球链模型,研究了形状各向异性、磁晶各向异性、层叠粒子数以及粒子间距对反磁化及其临界场、矫顽力的影响.此模型可用来解释取向钡铁氧体磁粉介质的反磁化机理. 关键词： 反磁化 多扁椭球链模型     

高密度磁记录用La-Zn替代锶铁氧体薄膜

用射频溅射装置制备了La-Zn替代磁铅石型锶铁氧体(SrM)薄膜(La_xSr_1-xZn_xFe_12-xO₁₉,0≤x≤0.4),通过对样品微结构及磁性的研究,发现替代可以有效控制薄膜中晶粒的生长,合适的替代量(x=0.4)可得到平均尺寸大约为12nm的六角片状晶粒.饱和磁化强度M_s随替代量x的增加出现极大值,而矫顽力H_c则呈上升趋势.同时替代使薄膜室温下的 关键词： 铁氧体薄膜 磁记录     

用激光增益获取弱增益拉曼模式的受激拉曼散射光谱

当酒精的弱增益拉曼模式处于罗丹明640染料分子的激光增益范围时，在由悬垂液滴构成的圆形谐振腔中，观察到乙醇分子C—H伸缩系列模中多个弱增益拉曼模式的受激拉曼散射（SRS）光谱.随着抽运光的增强，迅速增长的强增益拉曼模式的受激辐射抑制了其他弱增益模式的SRS，并导致染料激光的完全淬灭.通过分析圆形腔腔模的光子速率方程和激光染料分子的三能级粒子数速率方程，解释了观察到的实验现象. 关键词： 受激拉曼散射 悬垂液滴 弱拉曼增益模式 激光增益     

界面对Fe65Co35薄膜微结构和软磁性的影响

用不同的材料（Co₉₃Fe₇和Fe）作衬底层,利用磁控溅射法成功制备了Fe₆₅Co₃₅（主层）/衬底层结构的双层薄膜．通过X射线衍射和磁性测量发现,在不同的衬底上沉积的Fe₆₅Co₃₅薄膜的织构不同,并且（200）取向的Fe₆₅Co₃₅薄膜的面内各向异性和软磁性优于（110）取向的Fe₆₅Co_{35关键词： 65}Co₃₅薄膜')" href="#">Fe₆₅Co₃₅薄膜 衬底层 界面各向异性 软磁性     

Effects of underlayer materials and substrate temperatures on the structural and magnetic properties of Nd2Fe14B films

Thin films of Nd_2Fe_{14}B were fabricated on heated glass substrates by dc magnetron sputtering. Different material underlayers (Ta, Mo, or W) were used to examine the underlayer influence on the structural and magnetic properties of the NdFeB films. Deposited on a Ta buffer layer at 420℃, the 300 nm thick NdFeB films were shown to be isotropic. But when the substrate temperature T_s was elevated to 520℃, the Nd_2Fe_{14}B crystallites of (00l) plane were epitaxially grown on Ta (110) underlayer. In contrast, Mo (110) buffer layer could not induce any preferential orientation in NdFeB film irrespective of the substrate temperature or film thickness. The W buffer layer was found to be most effective for the nucleation of Nd_2Fe_{14}B crystallites with c-axis alignment perpendicular to the film plane when T_s<490℃. But at T_s=490℃ the magnetic layer became isotropic. The maximum coercivity obtained was about 995 kA/m for the 100nm film deposited on W underlayer at 490℃. These variations were tentatively explained in terms of the lattice misfit between the underlayer and the magnetic layer, combined with the considerations of underlayer morphologies.     

通过Ta，Al的添加改进纳米晶FeXN薄膜的结构和磁性

在本次工作中，制备了纳米晶FeAlN和FeTaN薄膜。虽然两种膜都展示了软磁性，但是观察到了不同的单轴各向异性。微结构的测量揭示了Ta的添加导致了N的更高溶解度，并且导致了更大的晶格膨胀和更大的压缩应力。单轴各向异性来源于N原子在a－Fe点阵中的各向异性分布。Al更容易与N发生反应，所以FeAlN膜中的a－Fe比FeTaN中的要纯，并且其应力是张应力。两种薄膜不同的各向异性可以由它们不同的微结构来解释。     

衍射主镜面外拼接误差分析

多子镜拼接的方法可实现大口径菲涅耳衍射透镜制作,但拼接误差会对光学系统的成像质量造成影响。通过衍射光线追迹和波前恢复的方法,正向得到了子镜沿自身x′轴倾斜、y′轴倾斜、z′轴平移等面外误差与对应波前误差Zernike系数的数据库。利用数据库基于反向传播神经网络优化算法反向建立波前误差Zernike系数与对应面外误差的非线性耦合映射模型,可实现通过输入Zernike系数完成对面外误差耦合扰动情况的快速求解,运用带有符号的数值判定面外误差的大小及方向。对该模型进行模拟数值计算,验证了该方法的精度及可靠性,为衍射拼接主镜的共面检测、装调提供理论依据。     

Magnetic Force Microscopy Study of Alternate Sputtered （001） Oriented L1o Phase FePt Films

We present a magnetic force microscopy study of alternate sputtered （001） oriented L1o phase FePt films. It is found that the root-mean-square value of phase shift of magnetic force images, （ △Ф）rms, can be used to characterize the perpendicular anisotropy for a series of specimens. Therefore, the considerable improvement of the perpendicular anisotropy after post-annealing can be characterized. In addition, the magnetic properties, magnetic and crystalline microstructures before and after post-annealing are compared for the typical [Fe5nm Pt5 nm]10 film with substrate temperature T8 = 500℃, single layer thickness d = 5 nm and total layer thickness D=100 nm to confirm the effect of post-annealing on improving the perpendicular anisotropy for Fe-Pt films.     

Differential System＇s Nonlinear Behaviour of Real Nonlinear Dynamical Systems

Chaos attractor behaviour is usually preserved if the four basic arithmetic operations, i.e. addition, subtraction, multiplication, division, or their compound, are applied. First-order differential systems of one-dimensional real discrete dynamical systems and nonautonomous real continuous-time dynamical systems are also dynamical systems and their Lyapunov exponents are kept, if they are twice differentiable. These two conclusions are shown here by the definitions of dynamical system and Lyapunov exponent. Numerical simulations support our analytical results. The conclusions can apply to higher order differential systems if their corresponding order differentials exist.     

磁性隧道结的隧穿磁电阻效应及其研究进展

文章概括地介绍了磁性隧道结（MTJs）的隧穿磁电阻（TMR）效应的产生机理和特点,主要用途和研究背景以及最近几年的研究进展和现状.对用Al2O3和MgO做绝缘势垒层的MTJs进行了对比,指出用MgO做绝缘势垒层的MTJs的优点.文章还阐明了交换偏置自旋阀（EB-SV）型MTJs的问题和不足,以及新兴的赝自旋阀（PSV）型MTJs的优势.文章最后总结了用于MTJs的各种铁磁层和绝缘势垒层材料,并对TMR材料今后的研究和开发作了展望.