Micromagnetism and Microstructure of Ferromagnetic Thin Film Systems

9818296 Bauer本项目的目标是从微观上理解（1）薄膜系统的微观结构与其磁性能之间的相互关系，以及（2）这些性能对膜厚度、表面活性剂、温度和磁场强度等参数的依赖性，使用自旋极化低能电子显微镜结合磁光克尔效应测量的新技术。研究重点是以下问题：（i）晶粒结构和界面的粗糙度以及清洁或吸附物覆盖的表面对磁畴结构的影响，（ii）铁磁层之间通过磁性或反铁磁间隔物的层间耦合，（iii）微结构对畴壁运动的影响;以及（iv）在亚微米尺度上，磁畴结构和磁壁运动对磁系统几何形状的依赖性。这一结果不仅对基本了解降维铁磁性有重要意义，而且对磁记录和传感器件的开发和优化也有重要意义。 %过去所有的电子设备都是基于电子具有电荷的事实。近年来，人们作出了巨大的努力来开发利用电子也有自旋这一事实的器件。这已经导致了新的高密度信息存储介质和基于非晶态金属膜的传感器。下一个世纪需要更高的存储密度和更小的传感器。为了达到这个目标，自旋系统的性质对它们的微观结构的依赖性必须得到更好的理解，因为它们是紧密耦合的。这可以最好地实现使用自旋极化低能电子显微镜的图像同时自旋分布和微观结构的新方法。这项研究不仅将为高新技术“自旋电子学”的发展做出重大贡献，同时还将为这一经济重要领域培养学生。

9818296BauerThe goal of this project is the microscopic understanding of (1) the interrelation between the microstructure of ultrathin film systems and their magnetic properties and (2) of the dependence of these properties upon parameters such as film thickness, surfactant, temperature and magnetic field strength, using the novel technique of spin-polarized low energy electron microscopy combined with magneto-optic Kerr effect measurements. The study focuses on the following problems: (i) the influence of grain structure and roughness of the interface and of the clean or adsorbate-covered surface on the magnetic domain structure, (ii) the interlayer coupling between ferromagnetic layers through nonmagnetic or antiferromagnetic spacers, (iii) the influence of the microstructure on the domain wall motion and (iv) the dependence of the domain structure and of the wall motion on the geometry of the magnetic system in submicron dimensions. The results are important not only for the basic understanding of ferromagnetism in reduced dimensions but also for the development and optimization of magnetic recording and sensing devices. %%%In the past all electronic devices were based on the fact that the electron has a charge. In recent years great efforts were made to develop devices which make use of the fact that the electron also has a spin. This has lead already to new high density information storage media and sensors based on ultrathin metallic films. Still higher storage densities and smaller sensors are needed in the next century. To reach this goal the dependence of the properties of spin systems upon their microstructure must be better understood because they are intimately coupled. This can be best achieved using the novel method of spin-polarized low energy electron microscopy which images simultaneously spin distribution and microstructure. The study will not only contribute significantly to the development of the new high technology "spintronics" but at the same time trains students for this economically important field.***