Coherent spin waves for emerging nanoscale magnonic logic architectures

信息技术（IT）已经渗透到现代社会生活的方方面面。IT的核心是能够以一种或另一种形式处理和存储信息的微型设备。目前，信息处理主要是在基于微小“晶体管”的半导体数据架构中进行的。相比之下，长期数据存储由磁性硬盘驱动器主导，其中信息以微小的“磁针”的方向存储，其两个相反的方向在二进制逻辑中表示“0”和“1”值。然而，预计半导体行业将在未来十年内达到小型化的极限，而能源消耗将变得越来越重要，无论是环境问题还是与便携式电池供电设备的使用保持一致。在这个项目中，我们的目标是展示一种新型信息技术设备的关键组件，它有可能导致在同一芯片上组合数据处理和存储。该设备将基于“磁力学”，其中波状的磁化扰动（“自旋波”）穿过并在图案磁道（“波导”）中相互作用以执行操作。我们建议构造一个自旋波源，使许多自旋波源的波性质相互联系；从技术上讲，这被称为“连贯性”。我们提出的自旋波源由放置在波导上的磁性纳米线天线组成。微波辐射会在天线中产生磁振荡，而磁振荡又会在附近的波导中产生自旋波。自旋波被提议作为逻辑信号载体，从而帮助它们与现有和未来的磁数据存储技术无缝集成。这种在单一架构内集成信号处理和存储的方法有望降低能耗和快速设备运行。此外，我们将探索自旋波如何与各种组件的磁构型相互作用。天线和波导的材料和几何形状导致磁化倾向于沿着它们的长度分布。然而，相反的磁化可以被设计成在波导内部相遇，从而形成一个称为“磁畴壁”的过渡区域。通过选择性地配置磁波导和天线的方向，包括结合磁畴壁，我们将能够编程磁器件的功能。我们建议使用的磁性材料不需要电力来保持其磁性（非挥发性），这意味着我们的设备在断电时将存储配置，因此，在打开开关时将立即启动。磁性元件的多种稳定配置和相关的多种功能也将为创造更复杂的设备提供机会，这些设备可以取代传统电子产品中的几个半导体晶体管。除了消费类电子产品外，这种设备还将有利于航空航天、太空和潜艇技术的应用，因为它们的不挥发性和抗辐射能力将大大节省重量和成本。该合作研究项目将由谢菲尔德大学材料科学与工程系和埃克塞特大学工程、数学和物理科学学院联合开展。谢菲尔德大学的团队将为该项目贡献他们在纳米技术和磁畴壁操纵方面的国际领先专业知识，而埃克塞特大学的团队将贡献他们在磁器件的动力学表征和理论建模方面的世界领先专业知识。通过联合他们的力量，两个团队将确保英国将保持在磁逻辑技术的前沿，特别是开辟新的跨学科领域的畴壁磁振学。

Information technology (IT) has penetrated all aspects of life in modern society. At the heart of IT are miniature devices that can process and store information in one or another form. Currently, the information is processed mainly within semiconductor based data architectures based on tiny "transistors". In contrast, long-term data storage is dominated by magnetic hard disk drives, within which the information is stored as direction of tiny "magnetic needles" the two opposite orientations of which represent "0" and "1" values in binary logics. However, the semiconductor industry is predicted to reach the limit of miniaturisation within the coming decade, while the energy consumption becomes increasingly important both for environmental concerns and to align with use in portable battery fed devices. In this project, we aim to demonstrate a key component of a novel device for information technology, which has the potential to lead to combined data processing and storage on the same chip. This device will be based upon 'magnonics', in which wave-like perturbations of magnetisation ('spin waves') travel through and interact in patterned magnetic tracks ('waveguides') to perform operations. We propose to construct a spin wave source such that the wave properties of many such sources are linked; technically, this is known as 'coherence'. Our proposed spin wave source consists of a magnetic nanowire antenna placed across the waveguides. Microwave radiation will create magnetic oscillations in the antennae, which in turn will induce the spin waves in the nearby waveguides.Spin waves are proposed as logic signal carriers, thereby assisting their seamless integration with existing and future magnetic data storage technologies. This integration of signal processing and storage within a single architecture promises reduced energy consumption and fast device operation. In addition, we will exploit how the spin waves interact with the magnetic configuration of the various components. The materials and geometry of the antennae and waveguides causes the magnetisation to prefer to lie along their length. However, opposite magnetisations can be engineered to meet within, say, the waveguide to create a transition region called a 'magnetic domain wall'. By selectively configuring the orientation of the magnetic waveguide and antennae, including incorporation of magnetic domain walls, we will be able to program the magnonic device functionalities. The magnetic materials we propose to use don't require power to retain their magnetisation (non-volatility), meaning our devices will store the configuration when powered off and, therefore, will be instantaneously bootable upon switch on. The multiple stable configurations of the magnetic components and associated multiple functionalities will also provide an opportunity for creating more complex devices that could replace several semiconductor transistors in conventional electronics. Apart from consumer electronics, the devices will be advantageous for use in aerospace, space and sub-marine technologies in which their non-volatility and resistance to radiation will allow vital weight and cost savings to be made. The collaborative research programme will be conducted jointly by the Department of Materials Science and Engineering at the University of Sheffield and the College of Engineering, Mathematics and Physical Sciences at the University of Exeter. The Sheffield team will contribute to the project their internationally leading expertise in nanotechnology and manipulation of magnetic domain walls, while the Exeter team will contribute their world leading expertise in dynamical characterization and theoretical modelling of magnonic devices. By joining their forces together, the two teams will ensure that UK will remain at the forefront at the magnetic logic technology, in particular opening the new interdisciplinary field of domain wall magnonics.