Excellence in Research: Nano-Structured Functional Ferromagnets

非技术摘要：磁致伸缩材料是指当暴露在外部磁场中时可以伸长或收缩的材料。具有可逆磁性的高磁致伸缩材料非常适合在传感器、执行器和水下通信设备等现代技术中的应用。这项研究推进了纳米结构铁磁体的科学知识，这些纳米结构铁磁体在小磁场下表现出巨大的机械响应。研究了各种磁性材料，包括块体和薄膜形式的金属合金和陶瓷。这项研究计划提供了独特的教育和培训的研究生和本科生在材料合成和最先进的表征技术。这些努力提高了少数族裔学生在科学和工程学科中的竞争力，并扩大了有才华的非裔美国科学家和工程师队伍，从而加强了高科技少数族裔劳动力。马里兰州高中的外展活动鼓励和鼓励高中生从事科学和工程。技术摘要：该奖项支持将小磁晶各向异性和大磁致伸缩相结合的磁性材料的研究。我们的假设是，导致这种不寻常的性质组合的基本机制是通过两相纳米结构打破理论上对单相固体有效的自旋-轨道耦合链。所研究的体系包括Fe-Ga、Al、Ge固溶体和纳米棋盘状的钴铁氧体，并用磁表征技术对其性质进行了研究。使用X射线和中子辐射的衍射技术确定了潜在的纳米结构。这些模型材料的原位应力下的透射电子显微镜也是阐明纳米结构在磁致伸缩中的作用的关键实验。这些活动旨在为这门材料课建立一个共同的科学基础。本科生和研究生都参与了这项研究，积累了磁性材料领域的研究经验和专业知识。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

NON-TECHNICAL SUMMARY:Magnetostrictive materials are those that can elongate or contract when exposed to an external magnetic field. Highly magnetostrictive materials with a reversible magnetic character are highly suited for applications in modern technology such as sensors, actuators, and underwater communication devices. This research advances scientific knowledge of nanostructured ferromagnets that display a large mechanical response under small magnetic fields. A variety of magnetic materials are studied, including metallic alloys and ceramics in the bulk and thin film forms. This research program offers unique opportunities in the education and training of graduate and undergraduate students in materials synthesis and state-of-the-art characterization techniques. These efforts increase the competitiveness of minority students in the Science and Engineering disciplines and expand the pool of talented African-American scientists and engineers, thereby enhancing the high-technology minority workforce. The outreach to Maryland high schools engages and encourages high-school students in science and engineering.TECHNICAL SUMMARY:This award supports research on magnetic materials combining small magnetocrystalline anisotropy with large magnetostriction. The hypothesis is that the fundamental mechanism giving rise to this unusual combination of properties consists of breaking the theoretical spin-orbit coupling link valid for single-phase solids via a two-phase nanostructures. The systems of study include Fe-Ga,Al,Ge solid solutions and nanostructured cobalt ferrite in the form of nano-chessboard whose properties are probed by magnetic characterization techniques. Diffraction techniques using x-ray and neutron radiation determine the underlying nanostructures. Transmission electron microscopy of these model materials under stress in situ are also crucial experiments to elucidate the role of the nanostructure in magnetostriction. These activities aim at the development of a common science foundation for this materials class. The engagement of both undergraduate and graduate students in this research builds research experience and expertise in the field of magnetic materials.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.