Skyrmion materials for spintronics

一个由数据中心组成的全球网络为我们免费获取新闻、社交媒体、信息和教育提供了动力，而这些我们认为是理所当然的。这些数据中心构成了互联网基础设施的一部分，它们是通过存储世界上绝大多数知识的磁记录技术实现的。然而，由于基本材料的限制，硅技术和硬盘驱动器最近都结束了几十年来在尺寸和速度上的指数级改进。能源效率的提高将对数据中心的能源使用产生重要影响，数据中心已经消耗了北美总电力的约2%，此外还有手机、便携式电子产品和可穿戴电子产品的预测指数级增长。作为世界上手性磁性薄膜研究的领先团队之一，我的团队定位于为高能效、高速磁存储器的技术需求提供新的解决方案。传统的存储介质将信息存储在闪存驱动器上的微型晶体管或磁性硬盘驱动器上的大型旋转盘片中，而手性磁存储器将把信息存储在纳米级圆柱形磁性结构中，这种结构自然形成于具有特定晶体对称性的磁性材料中。Skyrmion存储器的信息编码速度比闪存快1000倍，电流比传统磁畴小10万倍。在实际设备中使用skyrmions材料的主要障碍之一是大多数材料中的skyrmions只能在低于室温的温度下形成。该提案旨在通过使用高通量真空沉积方法，发现可以在室温以上产生skyrmions的新材料。利用达尔豪斯大学的组合溅射设备，可以在单一衬底上生长数百种合金成分。x射线分析将能够快速筛选合金，以识别那些具有正确晶体对称性的成分，电测量将确定它们的磁有序温度。然后，最佳候选材料将通过分子束外延以原子平面单晶形式合成，并用电子和扫描探针显微镜在纳米尺度上对其磁性结构进行成像。通过调整合金成分，可以控制天幕的大小，从而了解产生它们的基本相互作用。就像气泡从一锅沸水的边缘成核一样，天空粒子从膜的界面和边缘成核。然后，我们可以通过选择沉积在薄膜表面的材料来控制这种成核。然后，Skyrmions将通过纳米制造的电线通过电流来开发新的Skyrmions磁性存储器。

A global network of data centres powers the free access to news, social media, information and education that we take for granted. These data centres, which form part of the Internet's infrastructure, are made possible by magnetic recording technology that now stores the vast majority of the world's knowledge. However, both silicon technology and hard drives have recently seen the end of decades of exponential improvements in size and speed due to fundamental materials limitations. Improvements in energy efficiency will have important implications for the energy usage of data centres, which already consume approximately 2% of the total electricity in North America, as well as cell phones, portable electronics and the forecasted exponential growth of wearable electronics.As one of the leading groups in the world in chiral magnetic thin film research, my group is positioned to yield new solutions to the technological demands of highly energy-efficient, high-speed magnetic memories. Unlike conventional visions of storage media where bits of information are stored in microfabricated transistors on flash drives, or on the large spinning platters in magnetic hard disk drives, chiral based magnetic memories will store information in nanoscale cylindrical magnetic textures skyrmions that naturally form in magnetic materials with particular crystal symmetries. Skyrmion memories would encode information over 1000 times faster than flash memory and be moved by currents 100,000 times smaller than conventional magnetic domains. One of the major obstacles to using skyrmion materials in practical devices is that skyrmions in most materials only form at temperatures below room temperature. This proposal seeks to discover new materials that produce skyrmions well above room temperature by using high-throughput vacuum deposition methods. Using combinatorial sputtering facilities at Dalhousie University, hundreds of alloy compositions can be grown on a single substrate. X-ray analysis will enable rapid screening of the alloys to identify those compositions with the right crystal symmetry, and electrical measurements will determine their magnetic ordering temperature. The best candidate materials will then be synthesized in atomically flat, single-crystal form by molecular beam epitaxy and the magnetic structures will be imaged at the nanoscale with electron and scanning probe microscopies.By tuning the alloy composition, the size of the skyrmions will be controlled to understand the fundamental interactions that produce them. Just as bubbles nucleate from the edges of a pot of boiling water, skyrmions nucleate from film interfaces and edges. We can then control this nucleation by the choice of materials we deposit on the film surfaces. Skyrmions will then be pushed through nanofabricated wires by using electrical currents to develop new skyrmion magnetic memories.