Collaborative Research: Understanding Magnetostrictive Galfenol Physics for Micro- and Nano-scale Devices

合作研究：了解微型和纳米级器件的磁致伸缩加酚物理

• 批准号: 1231993
• 负责人: Bethanie Stadler
• 金额: $ 29.64万
• 依托单位: University of Minnesota-Twin Cities
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-08-15 至 2015-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1231993&HistoricalAwards=false
• 关键词: Collaborative; Research; Understanding; Magnetostrictive; Galfenol

The proposed research focuses on structured analytical and experimental analysis of magnetostriction in iron-gallium (Galfenol) thin films and nanowires to advance understanding of the magnetostrictive physics at this scale and to enable transformative new micro- and nano-scale device functionality. This alloy system has the distinct advantage of having high strains in response to magnetic fields (400ppm) while also exhibiting the mechanical ductility and strength of iron. The ability to electrodeposit this active material is possible due to preliminary work which overcame the difficulty of Ga oxidation in aqueous electrolytes, and which therefore enabled FeGa metallic alloys to be fabricated as thin films and nanowires. The intellectual merit of this research includes that insights from study of the proposed micro- and nano-scale test devices will lead to a deep understanding of the exciting device physics needed to facilitate utilizing magnetostriction at the nanoscale such as in artificial cilia sensors and actuators that mimic biological transducers in nature. As the only highly responsive material possible as ductile nanowires and conformal (nonplanar) thick films, this research is also expected to lead to the creative, new concepts for transformative sensors and actuators at the micro- and nano-scale. This work proceeds with an original plan to make the leap from materials science to devices with four important goals. The first goal is a simple, yet critical, step of measuring magnetostriction of electrodeposited Galfenol thin films as a function of composition, crystallographic orientation and magnetic domain orientation. A capacitance bridge will be used to measure the magnetostriction of these films and the optimal deposition parameters will be used in the subsequent goals. The second goal is to make a non-contact torque sensor as a test device to study the device physics of Galfenol films. The torque sensors will be evaluated in an existing rotating shaft torque test stand. The third goal involves high-risk, high-payoff measurements of magnetostriction in nanoscale devices (10-100nm diameter Galfenol nanowires). Wires with the right composition, crystal structure, and even necessary segmentation have been previously made, but measuring magnetostriction at this scale is difficult due to unknown strains, very small magnetic fields (from single wires), and general size constraints. Here, measurements of giant magnetoresistance (GMR) in individual nanowires will be used to determine the effect of applied tensile and compressive strains. In addition, magnetic force microscopy will be used to observe magnetization rotation in bent nanowires to verify GMR results. The fourth and last goal will involve making high-resolution tactile sensors using Galfenol nanowires to learn more about their behavior and integration into devices. This research will have impact in a broad variety of fields including spintronics (FeGa on GaAs), vibration sensors, energy harvesters as cantilevers and/or nanowires, and a wide range of sensors and actuators using non-contact mechano-magneto coupling (e.g. conformal non-contact torque sensors and structural health monitoring sensors). This research will impact the education of undergraduates via REU programs at both universities, and especially underrepresented students via faculty mentoring programs. Graduate students will benefit from course development that will include the research results from this project and from interactions with industry via industrial centers with annual reviews, journal clubs, and seminars. Finally, the PIs' will train students in outreach to k-12 students to continue the broad impact in the next generation.

拟议的研究重点是铁镓（Galfenol）薄膜和纳米线中磁致伸缩的结构化分析和实验分析，以增进对这种规模的磁致伸缩物理的理解，并实现变革性的新微米和纳米级器件功能。该合金系统具有独特的优势，即对磁场具有高应变 (400ppm)，同时还表现出铁的机械延展性和强度。电沉积这种活性材料的能力是可能的，因为前期工作克服了水性电解质中 Ga 氧化的困难，因此使得 FeGa 金属合金能够被制造为薄膜和纳米线。这项研究的智力价值包括，对所提出的微米和纳米级测试装置的研究的见解将导致对促进在纳米级利用磁致伸缩所需的令人兴奋的装置物理的深入了解，例如模仿自然界生物传感器的人工纤毛传感器和执行器。作为唯一可能作为延展性纳米线和保形（非平面）厚膜的高响应材料，这项研究也有望为微米和纳米尺度的变革性传感器和执行器带来创造性的新概念。这项工作按照最初的计划进行，旨在实现从材料科学到设备的跨越，具有四个重要目标。第一个目标是测量电沉积 Galfenol 薄膜的磁致伸缩作为成分、晶体取向和磁畴取向的函数的简单但关键的步骤。将使用电容电桥测量这些薄膜的磁致伸缩，并在后续目标中使用最佳沉积参数。第二个目标是制作非接触式扭矩传感器作为测试装置来研究Galfenol薄膜的器件物理特性。扭矩传感器将在现有的旋转轴扭矩测试台上进行评估。第三个目标涉及纳米级设备（直径为 10-100 纳米的 Galfenol 纳米线）中磁致伸缩的高风险、高回报测量。具有正确成分、晶体结构甚至必要分割的线材之前已经制成，但由于未知的应变、非常小的磁场（来自单线）和一般尺寸限制，测量这种规模的磁致伸缩很困难。在这里，对单个纳米线中巨磁阻（GMR）的测量将用于确定施加的拉伸和压缩应变的影响。此外，磁力显微镜将用于观察弯曲纳米线中的磁化旋转，以验证 GMR 结果。第四个也是最后一个目标将涉及使用 Galfenol 纳米线制造高分辨率触觉传感器，以了解有关其行为和集成到设备中的更多信息。这项研究将在广泛的领域产生影响，包括自旋电子学（GaAs 上的 FeGa）、振动传感器、作为悬臂和/或纳米线的能量采集器，以及使用非接触式机械磁耦合的各种传感器和执行器（例如共形非接触式扭矩传感器和结构健康监测传感器）。这项研究将通过两所大学的 REU 项目影响本科生的教育，特别是通过教师指导项目影响代表性不足的学生。研究生将受益于课程开发，其中包括该项目的研究成果，以及通过工业中心的年度评论、期刊俱乐部和研讨会与工业界的互动。最后，PI 将培训学生向 k-12 学生进行推广，以继续对下一代产生广泛的影响。