Synthetic antiferromagnetic skyrmions

合成反铁磁斯格明子

• 批准号: 2281911
• 金额: --
• 依托单位: University of Leeds
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2019
• 资助国家: 英国
• 起止时间: 2019 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2281911
• 关键词: Synthetic; antiferromagnetic; skyrmions

In this project we will study magnetic skyrmions, nanoscale swirls of spins that possess a special topology. They appear in properly designed magnetic multilayers at room temperature and are candidates for next-generation data storage technology. It is now over a decade since the carbon footprint of the internet grew larger than that of commercial air travel, much of this energy is used to physically spin hard disks, write data to them, and write and refresh volatile memory. To drive skyrmions along a crystal using spin torque requires several orders of magnitude less current density then driving magnetic domains under ideal conditions, but this is not seen in practice in these systems so far. Magnetic skyrmions thus offer the prospect of vastly reducing the energy needed to write and store digital data if their properties can be controlled. Two current challenges are that skyrmions do not move in the direction they are pushed by an electrical current, but actually move at an angle, due to the so-called skyrmion Hall effect arising from their topological charge, and are also expected to have reduced mobility as the size is reduced, affecting the reliability and speed of device operation. To address these issues, here we will stabilise skyrmions in synthetic antiferromagnetic multilayers and study their current-driven dynamics, based two recent breakthroughs in the Leeds condensed matter physics group: our being able to stabilise skyrmions as a topological structure in a magnetic multilayer (Zeissler et al., Nature Nanotech., 2018), and being able to move coupled topological defects-domain walls-at low current density in a pair of antiferromagnetically coupled layers (Lepadatu et al., Sci. Reports, 2017). Cancelling out the topological charge by using a synthetic antiferromagnet is expected to overcome both the skyrmion Hall angle and reduced mobility problems. The project is partially sponsored by the National Physical Laboratory (NPL), in Teddington near London, through the CASE scheme. We expect close collaboration with NPL in the project, including secondments at NPL by the successful candidate.

在这个项目中，我们将研究磁性斯格明子，即具有特殊拓扑结构的纳米级自旋漩涡。它们在室温下出现在经过适当设计的磁性多层中，是下一代数据存储技术的候选者。十多年来，互联网的碳足迹已经超过商业航空旅行的碳足迹，其中大部分能源用于物理旋转硬盘、向硬盘写入数据以及写入和刷新易失性内存。使用自旋扭矩沿晶体驱动斯格明子所需的电流密度比理想条件下驱动磁域的电流密度低几个数量级，但迄今为止在这些系统的实践中还没有看到这种情况。因此，如果磁性斯格明子的特性可以控制，那么它们有望大大减少写入和存储数字数据所需的能量。当前的两个挑战是，斯格明子不会沿着电流推动的方向移动，而是实际上以一定角度移动，这是由于其拓扑电荷产生的所谓斯格明子霍尔效应，并且预计其迁移率也会降低随着尺寸的减小，影响了器件运行的可靠性和速度。为了解决这些问题，我们将在这里稳定合成反铁磁多层中的斯格明子，并研究它们的电流驱动动力学，基于利兹凝聚态物理小组最近的两项突破：我们能够稳定斯格明子作为磁性多层中的拓扑结构（蔡斯勒等人，自然纳米技术。，2018），并且能够以低电流密度移动一对反铁磁耦合层中的耦合拓扑缺陷（磁畴壁）（Lepadatu等人，科学报告，2017）。通过使用合成反铁磁体消除拓扑电荷有望克服斯格明子霍尔角和迁移率降低的问题。该项目由位于伦敦附近特丁顿的国家物理实验室 (NPL) 通过 CASE 计划部分赞助。我们期望在该项目中与 NPL 密切合作，包括成功候选人借调到 NPL。