Overseas Travel Grant: XMCD investigation of spin-orbit coupled heavy-metal/ferromagnet heterostructures at the Advanced Light Source, Berkeley

这项海外旅行拨款提案寻求EPSRC的支持，以支付我们在先进光源劳伦斯伯克利国家实验室研究重金属/铁磁体多层自旋轨道耦合的光束时间最后阶段的旅行和住宿费用。自旋轨道耦合是近年来自旋电子学研究的热点，它提供了一种革命性的方法来操纵自旋，而不需要铁磁体来驱动经典的自旋电子器件。与铁磁体接触的重金属中的自旋轨道耦合也被用于产生新的拓扑物体，如磁性天空，为下一代超密集数据存储提供了可能。此外，最近的工作表明，重金属/铁磁体异质结构中的自旋轨道耦合与超导之间存在基本联系，这为开发自旋轨道耦合驱动的自旋电子学的超导模拟提供了可能性。虽然从这些异质结构设计自旋轨道耦合铁磁体的重要性已经确立，但一些与材料相关的问题仍然存在。例如，自旋轨道耦合强度作为重金属或铁磁体性质的函数的确切依赖关系仍然知之甚少。使用不同铁磁体和重金属的综合研究将使我们能够了解这些系统中自旋轨道耦合的微观起源以及操纵它的方法。为了研究这一点，我们获得了x射线磁圆二色（XMCD）光束时间在6.3.1。从2017年到2018年，伯克利先进光源的光束线。我们已经参加了18个班次，本提案寻求资金来赞助我们最后6个班次的波束时间（提案号ALS-09050，附上波束时间计划函）。该光束线提供高精度的XMCD测量，具有快速的磁场反转，最大限度地减少扫描时间。高度自动化的光束线还允许在一次装载中测量多个样品，使其成为我们涉及大量样品的研究的理想选择。从这个光束时间得到的结果将允许我们在未来定量地将材料参数与自旋轨道耦合的强度联系起来，从而为实验人员提供一个选择材料的列表，以专门定制这些特性。这不仅有利于自旋电子学领域，而且还将使我们巩固对自旋轨道耦合在超导自旋电子学中新发现的作用的理解。

This Overseas Travel Grant proposal seeks support from the EPSRC to cover the expenses related to travel and accommodation costs for the final phase of our beam time at the Advanced Light Source, Lawrence Berkeley National Laboratory to study the spin-orbit coupling in heavy-metal/ferromagnet multilayers. Spin-orbit coupling has recently been under intense focus in spintronics research, offering a revolutionary way to manipulate spins without ferromagnets which has driven classical spintronic devices. Spin-orbit coupling in heavy-metals in contact with ferromagnets has also been utilised to generate novel topological objects like magnetic skyrmions that offers the possibility of next-generation of ultra-dense data storage. Furthermore, recent work has shown a fundamental connection between spin-orbit coupling in heavy-metal/ferromagnet heterostructres and superconductivity that offers the possibility to develop a superconducting analogue of spin-orbit coupling-driven spintronics.Although the importance of spin-orbit coupled ferromagnets designed from these heterostructures is established, several materials-related questions remain. For example, the exact dependence of the strength of the spin-orbit coupling as a function of the nature of heavy-metal or ferromagnet remains poorly understood. A comprehensive study using different ferromagnets and heavy-metals will allow us to understand the microscopic origins of the spin-orbit coupling in these systems and ways to manipulate it. To investigate this, we have been awarded 24 shifts of X-ray Magnetic Circular Dichroism (XMCD) beamtime at the 6.3.1. beamline at the Advanced Light Source in Berkeley from 2017-2018. We have already attended 18 shifts and this proposal seeks funding to sponsor our last 6 shifts of beamtime (Proposal number ALS-09050, attached beamtime schedule letter). This beamline offers high accuracy XMCD measurements with a rapid magnetic field reversal minimising scan time. The highly-automated beamline also allows several samples to be measured in one loading making it ideal for our study involving a large number of samples.The results from this beamtime will allow us in future to quantitatively relate material parameters with the strength of spin-orbit coupling, thereby providing experimentalists a list to select materials from to specifically tailor the properties of these. Not only this will benefit the spintronics community, but will also allow us to consolidate our understanding of the newly discovered role of spin-orbit coupling in superconducting spintronics.