Soft x-ray studies of nanomagnetic and spintronic materials at Brookhaven National Laboratory

利兹凝聚态物理小组作为同步辐射的常规用户已经有六年多的时间了，在那里，独特的元素对极化软x射线的磁性敏感性为我们研究各种纳米磁系统的无序性、各向异性和迟滞性做出了巨大贡献。在此，我们请求旅费资助，使我们能够在该设施新的两年用户计划中开展两项主要研究。第一个是由布鲁克海文功能纳米材料中心制造的纳米磁体阵列的软x射线磁散射，它表现出受挫的几何形状：虽然潜在的物理结构是周期性的，但由于受挫，磁性结构将只显示短范围的有序。离镜面磁散射将使我们能够将这种无序描述为样品阵列几何形状、磁场和温度的函数，从而为实际空间成像技术提供补充信息。第二个领域是磁性纳米团簇的研究，由气相聚集形成，并作为磁性多层堆叠的一部分沉积，如隧道结。我们有能力生成非常窄且控制良好的大小分布，因此大小依赖。在这里，我们将使用XMCD光谱研究自旋轨道矩比和化学成分，例如周围隧道阻挡材料的氧化。与类似的欧洲设施不同，nssls的同步加速器光束时间没有提供资金来支持前往该设施的旅行。这些实验是我们正在进行的利兹和伊斯兰国之间非常成功的磁散射联合方案的一部分。申请的旅费和生活津贴只允许一个三人小组前往布鲁克海文进行为期五周的实验，以便每天24小时进行实验，并在CFN进行样品制作并在会议上展示我们的结果。

The Leeds Condensed Matter Physics Group have been regular users of synchrotron radiation at the NSLS now for over six years, where the unique element-specific sensitivity to magnetism of polarized soft x-rays has made great contributions to our research in studying disorder, anisotropy and hysteresis in a variety of nanomagnetic systems. Here we request travel funding to allow us to pursue here two main avenues of research in our new two year user programme at that facility. The first is soft x-ray magnetic scattering from arrays of nanomagnets, fabricated at the Brookhaven Center for Functional Nanomaterials, which exhibit frustrated geometries: whilst the underlying physical structure is periodic, the magnetic structure will display only short range order due to the frustration. Off-specular magnetic scattering will allow us to characterize this disorder as a function of sample array geometry, magnetic field, and temperature, yielding complementary information to real space imaging techniques. The second area is in the study of magnetic nanoclusters, formed by gas-phase aggregation and deposited as part of a magnetic multilayer stack such as a tunnel junction. We have the capability to produce very narrow and well-controlled size distributions, so size dependences. Here we will study spin-orbit moment ratios and chemical composition, such as oxidation from surrounding tunnel barrier material, using XMCD spectroscopy. Unlike similar european facilities, synchrotron beamtime at the NSLS does not come with money to support travel to the facility. The experiments form part of our ongoing and highly successful joint programme on magnetic scattering between Leeds and ISIS. The grant request is for travel and subsistence funds only to allow a team of three people to travel to Brookhaven for five weeklong periods in order to operate the experiment 24 hours a day, as well as carry out sample fabrication at the CFN and present our results at conferences.