Overseas Travel Grant: XMCD-PEEM study of the spin structure and spin torque in magnetic nanocontacts at the Advanced Light Source (ALS)

海外旅行补助金：先进光源 (ALS) 下磁性纳米接触中自旋结构和自旋扭矩的 XMCD-PEEM 研究

• 批准号: EP/G037124/1
• 负责人: Yongbing Xu
• 金额: $ 0.4万
• 依托单位: University of York
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2008
• 资助国家: 英国
• 起止时间: 2008 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FG037124%2F1
• 关键词: Overseas; Travel; Grant; XMCD; PEEM

This overseas travel grant application is to seek the support from the EPSRC to cover the travel and accommodation costs of our beam time at the Advanced Light Source (ALS) to study the spin torque effect in magnetic nanocontact, one of the most exciting topics of spintronics. The DTI has stated that, 'by 2015 spintronics technology will be the only way to make electronic devices smaller and more efficient -by then, existing semiconductors and semiconductor materials, like silicon, will have exhausted their capability for miniaturization.' [DTI Global Watch magazine, July /August 2005]. This is a growing interest in the use of spin-polarised current rather than the external magnetic fields to switch the spintronic devices. The current-induced magnetization switching, well known as spin-torque effects, can locally switch a magnetic element to avoid cross-talk and reduce the power consumption. Due to the spin and momentum transfer, the spin-polarised current can move away a domain wall trapped in a magnetic nanocontact, or switch the magnetic sub-layer in a GMR-type nanopillar structure. Over the last few years, there are several Nature and Science papers reporting the discovery of this effect and its great potentials, and during the 52nd Annual Conference on Magnetism and Magnetic Materials last November in Tampa, Florida, there were around 150 invited and contributed presentations on spin-torque effect and its applications. We have been awarded 12 shifts of beamtime at the Beamline 11.0.1.1 at the Advanced Light Source, USA, to study the spin structure and spin torque in magnetic nanocontact using x-ray magnetic circular dichroism in photoemission electron microscopy (XMCD-PEEM) (Proposal Number: ALS-02778, see the attached letter). We have also been awarded a new EPSRC project (EP/G0100641/1) with a PhD student to work on this topic (Note: This new EPSRC doesn't cover the travel and accommodations costs for the ALS beamtime). The 11.0.1 PEEM3 beamline at ALS with a spatial resolution of better than 20 nm offers a superior technique to probe both the spin configuration and orbital moment in magnetic nanocontacts, which is expected to provide unique information to understand the mechanisms of spin-torque effect and domain wall scattering, both depending on the spin-orbital exchange coupling. In specifically during this project in the ALS, we will measuring the spin configurations and spin and orbital moments in FeNi magnetic nanocontacts, and to investigating the dependence of the critical current density and domain wall magneto-resistance nanocontacts sizes in the FeNi nanocontacts.For the future work, we are applying for the beamtime to the Diamond NanoScience beamline (I06), as described in our new EPSRC grant proposal. The experiences to be obtained from our beamtime in ALS as described in this project will help the Diamond's beamline I06 to carry out the work in this new area. Apart from the FeNi to be measured in ALS in this project, we are planning to study both the spin structures and the spin and orbital moments as a function of the magnetic nanocontact size and the film thickness in polycrystalline Ni and single crystal Fe and Co in the Diamond's beamline I06. Our final objective is to determine suitable materials, crystal structures, geometries and sizes of magnetic nanocontacts with the aim to achieve large current-induced resistance changes and low critical current density for spintronics applications.

这项海外旅费资助申请是为了寻求EPSRC的支持，以支付我们在先进光源（ALS）的光束时间的旅行和住宿费用，以研究磁性纳米接触中的自旋扭矩效应，这是自旋电子学最令人兴奋的课题之一。DTI表示，“到2015年，自旋电子学技术将是使电子设备更小和更高效的唯一方法-到那时，现有的半导体和半导体材料，如硅，将耗尽其小型化的能力。“[贸易与工业部《全球观察》杂志，2005年7月/8月]。利用自旋极化电流而不是外部磁场来切换自旋电子器件的兴趣越来越大。电流感生的磁化翻转，即众所周知的自旋力矩效应，可以局部地切换磁性元件以避免串扰并降低功耗。由于自旋和动量转移，自旋极化电流可以移走磁性纳米接触中捕获的畴壁，或者切换GMR型纳米柱结构中的磁性子层。在过去的几年里，有几篇自然和科学论文报道了这种效应的发现及其巨大的潜力，去年11月在佛罗里达的坦帕举行的第52届磁性和磁性材料年会上，大约有150个关于自旋扭矩效应及其应用的邀请和贡献。我们已经在美国先进光源的Beamline11.0.1.1上获得了12个光束时间偏移，以研究磁纳米接触中的自旋结构和自旋扭矩，使用光电子发射电子显微镜（XMCD-PEEM）中的X射线磁性圆二色性（提案编号：ALS-02778，见所附信件）。我们还获得了一个新的EPSRC项目（EP/G 0100641/1），该项目由一名博士生参与（注：这个新的EPSRC项目不包括ALS beamtime的旅行和住宿费用）。ALS的11.0.1 PEEM 3光束线的空间分辨率优于20 nm，提供了一种上级技术来探测磁性纳米接触中的自旋构型和轨道矩，这有望为理解自旋扭矩效应和畴壁散射的机制提供独特的信息，这两者都取决于自旋-轨道交换耦合。特别是在ALS的这个项目中，我们将测量FeNi磁性纳米接触中的自旋配置和自旋和轨道矩，并研究FeNi纳米接触中临界电流密度和畴壁磁阻纳米接触尺寸的依赖关系。对于未来的工作，我们正在申请Diamond NanoScience光束线（I 06）的束时间，如我们新的EPSRC资助提案中所述。在本项目中所描述的ALS中从我们的束时间中获得的经验将有助于Diamond的束线I 06在这一新领域开展工作。除了在ALS中测量的FeNi外，我们还计划在金刚石光束线I 06中研究多晶Ni和单晶Fe和Co中的自旋结构以及自旋和轨道矩作为磁性纳米接触尺寸和膜厚度的函数。我们的最终目标是确定合适的材料，晶体结构，几何形状和尺寸的磁性纳米接触的目的是实现大的电流感应电阻变化和低临界电流密度的自旋电子学应用。