Magnetic X-ray imaging of patterned NiFe arrays

自组装和图案化磁性纳米结构由于其在未来纳米技术中的巨大潜力，目前是人们非常感兴趣的主题。高密度磁记录是有望从图案化介质的使用中受益的一个领域，其潜在存储密度高达当前磁盘驱动器中可用的1000倍。除了技术上的好处，图案化的纳米磁阵列为在模型系统中研究基础和纳米磁性方面提供了一个很好的机会。因此，与非图案化薄膜材料和块体系统相比，它们具有天然的优势。本文利用X射线透射式显微镜(XM)和光电发射电子显微镜(PEEM)研究了NiFe的图案化阵列的纳米磁性。利用美国伯克利实验室先进光源(ALS)提供的最先进的设施，我们希望对纳米磁点中的磁畴结构进行观察实验。最近用诸如MOKE的宏观技术观察到，图案中元素的特定几何构型(即正方形或六边形)可能导致与图案的物理结构各向异性相关的元素之间的磁相互作用。结果，作为磁记录的基本特性的磁化反转可能受到图案的对称性的影响。用XM和XPEEM可以无创地直接观察磁畴结构，可以直接证明磁化是如何受到局部磁场的影响的，以及相邻磁矩之间的相互作用和它们的对称性是否在再磁化过程中起着关键作用。在XM测量以及剩余状态的情况下，调查将作为外加磁场的函数来执行，从而允许观察在再磁化过程中磁组态的演变。

Self-assembled and patterned magnetic nanostructures are currently the subject of much interest due to their enormous potential in future nanotechnology. High density magnetic recording is one area which promises to benefit from a move towards the use of patterned media, with potential storage densities up to 1000 times higher than currently available in magnetic disk drives. As well as the technological benefit patterned nanomagnetic arrays offer a great opportunity to study aspects of fundamental and nanoscopic magnetism in model systems. As such they possess natural advantages over non-patterned thin film materials and bulk systems. Here we propose to carry out studies of nanomagnetic properties of patterned arrays of NiFe with X-ray transmission microscopy (XM) and Photo Emmission Electron Microscope (PEEM). Using the state-of the art facilities available at the Advanced Light Sourse (ALS), Berkeley laboratories, US, we would like to perform experiments on the observation of the magnetic domain structure in the nanoscopic magnetic dots. It has been recently observed with macroscopic techniques, such as MOKE, that a specific geometric configuration of elements in a pattern (i.e. square or hexagonal) may lead to magnetic interactions between the elements anisotropically correlated with the physical structure of the pattern. As a result, magnetisation reversal, which is the fundamental property in magnetic recording, can be affected by the symmetry of the pattern. A direct observation of the magnetic domain structure, which can be done non-invasively with XM and XPEEM, can directly demonstrate how the magnetisation is affected by the local magnetic field and whether the interactions between the neighboring moments and their symmetry play a crucial role in the remagnetisation process. In case of XM measurements, as well as the remanent state the investigation will be performed as function of the applied field allowing to observe the evolution of the magnetic configurations during the remagnetising process.