SHF: Small: Pipelined and wireless ultra-low power straintronics: An acoustically clocked combinational and sequential nanomagnetic architecture

SHF：小型：管道式和无线超低功耗应变电子学：声学时钟组合和顺序纳米磁性架构

• 批准号: 1216614
• 负责人: Jayasimha Atulasimha
• 金额: $ 44万
• 依托单位: Virginia Commonwealth University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-07-01 至 2016-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1216614&HistoricalAwards=false
• 关键词: SHF; Small; Pipelined; wireless; ultra

Elliptical single-domain nanomagnets with two stable magnetization orientations are far more energy-efficient as logic switches than traditional transistors. However, the method employed to switch them must be energy-efficient as well in order to build ultra-low-power nanomagnetic logic and memory paradigms. It has been theoretically shown that using multiferroic (magnetostrictive-piezoelectric) nanomagnets, whose magnetization can be flipped with strain generated by a tiny electrostatic potential applied across the piezoelectric layer, results in a remarkably energy-efficient switching scheme. It reduces the dissipation in the switching/clocking circuit by four orders of magnitude at a clock rate of ~ 1 GHz compared to other nanomagnet switching schemes. While this is attractive, an unattractive trait of nanomagnetic logic chains is that in order to build a pipelined architecture and hence retain an acceptable bit transfer rate, each magnet must be clocked individually. This necessitates contacting each magnetic with a contact line, which imposes a Herculean lithographic burden. The PIs propose to overcome this problem completely by designing and fabricating a novel acoustic scheme for clocking that allows pipelining and at the same time does not require contacts to every magnet, thereby completely lifting the lithography burden. A surface acoustic wave (SAW) launched in the substrate, and slowed down with periodically placed masses, generates strain in an array of magnets in the correct sequence for bit transfer, as long as the spacing between the magnets is one quarter of the SAW?s wavelength. With this scheme, the energy dissipation in a gate operation at room temperature can be very low. This project will: (i) design combinational and sequential logic based on acoustically clocked magnetostrictive nanomagnets acting as logic switches, as well as perform extensive simulations using the stochastic Landau-Lifshitz-Gilbert (LLG) equation to understand and optimize reliability and fault tolerance in the presence of thermal noise; (ii) experimentally demonstrate pipelined unidirectional logic flow, and (iii) develop comprehensive coupled models for the switching dynamics of nanomagnets stressed by surface acoustic wave (SAW). This research will result in a novel computational paradigm whose astonishing energy efficiency combined with very little lithographic burden could enable the production of cheap, high yield and extremely low power processors. Such processors would consume so little energy that they can be run off the energy harvested from the environment. This could open up hitherto unimaginable applications such as medically implanted processors powered only by the motion of the patient's body, or processors that monitor the structural health of bridges and buildings while being powered by vibrations caused by wind or traffic. Integration of this research with education and mentoring will result in traditional training activities such as guiding two doctoral students who will gain multidisciplinary skills in advanced nanofabrication, nanocharacterization and modeling, as well as undergraduate projects on SAW devices and nanofabrication of magnetostrictive nanomagnets that will be mentored by the PI and co-PI?s doctoral students. Other innovative outreach programs will include holding workshops on nanomagnets and computing for high school students through the Math Science Innovation Center (MSIC) and incorporating diversity into outreach programs by hosting under-represented K-12 students in summer with the help of VCUs Richmond Area Program for Minorities in Engineering (RAPME) program. These students will perform nanolithography under supervision and study the magnetic structures they create with MFM.

具有两个稳定磁化方向的椭圆单畴纳米磁体作为逻辑开关比传统晶体管更加节能。然而，用于切换它们的方法也必须是节能的，以便构建超低功耗纳米磁性逻辑和存储范例。理论上已经表明，使用多铁性（磁致伸缩-压电）纳米磁体，其磁化可以通过施加在压电层上的微小静电势产生的应变来翻转，从而产生非常节能的切换方案。与其他纳米磁体开关方案相比，它在时钟速率约为 1 GHz 时将开关/时钟电路中的功耗降低了四个数量级。虽然这很有吸引力，但纳米磁性逻辑链的一个不吸引人的特征是，为了构建流水线架构并因此保持可接受的位传输速率，每个磁体必须单独计时。这需要将每个磁体与接触线接触，这会带来巨大的光刻负担。 PI 提议通过设计和制造一种新颖的声学时钟方案来完全克服这个问题，该方案允许流水线操作，同时不需要接触每个磁体，从而完全减轻光刻负担。 只要磁体之间的间距是 SAW 的四分之一，在基板中发射的表面声波 (SAW) 并随着周期性放置的质量而减慢，就会以正确的顺序在磁体阵列中产生应变以进行位传输？ s 波长。通过这种方案，室温下栅极操作的能量耗散可以非常低。该项目将：(i) 设计基于声控磁致伸缩纳米磁体作为逻辑开关的组合逻辑和顺序逻辑，并使用随机 Landau-Lifshitz-Gilbert (LLG) 方程进行广泛的模拟，以了解和优化可靠性和容错能力存在热噪声； (ii) 通过实验演示管道式单向逻辑流，以及 (iii) 开发用于受表面声波 (SAW) 应力的纳米磁体开关动力学的综合耦合模型。这项研究将产生一种新颖的计算范式，其惊人的能源效率与极少的光刻负担相结合，可以实现廉价、高产量和极低功耗处理器的生产。这种处理器消耗的能量非常少，可以利用从环境中收集的能量来运行。这可能会开辟迄今为止难以想象的应用，例如仅由患者身体的运动供电的医疗植入处理器，或者在由风或交通引起的振动供电的同时监控桥梁和建筑物的结构健康状况的处理器。这项研究与教育和指导相结合将导致传统的培训活动，例如指导两名博士生，他们将获得先进纳米制造、纳米表征和建模方面的多学科技能，以及将指导的关于声表面波器件和磁致伸缩纳米磁体纳米制造的本科项目由 PI 和 co-PI 的博士生完成。其他创新的外展项目将包括通过数学科学创新中心 (MSIC) 为高中生举办纳米磁体和计算研讨会，以及在弗吉尼亚联邦大学里士满地区项目的帮助下，在夏季接待代表性不足的 K-12 学生，将多样性纳入外展项目中工程少数群体 (RAPME) 计划。这些学生将在监督下进行纳米光刻，并研究他们用 MFM 创建的磁性结构。