Skyrmion materials for spintronics

全球数据中心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，而我们认为这是理所当然的。这些数据中心是互联网基础设施的一部分，由磁记录技术实现，现在存储了世界上绝大多数的知识。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方面的指数级增长。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约2%的总电力，以及手机、便携式电子产品和可穿戴电子产品的预期指数增长。 作为手性磁性薄膜研究的世界领先团队之一，我的团队致力于为高能效、高速磁性存储器的技术需求提供新的解决方案。与传统的存储介质不同，信息比特存储在闪存驱动器上的微型制造晶体管中，或存储在磁性硬盘驱动器中的大型旋转盘片上，基于手性的磁存储器将以纳米级圆柱形磁性结构Skyrmion存储信息，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存储器编码信息的速度将比闪存快1000多倍，并且可以通过比传统磁区小10万倍的电流移动。在实际设备中使用Skyrmion材料的主要障碍之一是，大多数材料中的Skyrmion只能在低于室温的温度下形成。这项提议寻求通过使用高通量真空沉积方法来发现产生远高于室温的Skyrmions的新材料。利用达尔豪西大学的组合溅射设备，可以在一个衬底上生长数百种合金成分。X射线分析将使快速筛选合金以确定那些具有正确晶体对称性的成分，而电学测量将确定它们的磁有序温度。最好的候选材料将通过分子束外延以原子扁平的单晶形式合成，并将使用电子显微镜和扫描探针显微镜在纳米尺度上成像磁性结构。 通过调整合金成分，天子的大小将得到控制，以了解产生它们的基本相互作用。就像气泡从沸水锅的边缘成核一样，Skyrmions从薄膜界面和边缘成核。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，通过使用电流来开发新的Skyrmion磁存储器，Skyrmion将被推过纳米级的金属丝。

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.