Electrical switching of magnetic devices by voltage-controlled proton insertion for low-power, high-performance data storage and computing

随着传统的硅基电子器件接近基本物理极限，迫切需要新的材料和器件来满足当今信息化社会对低功耗、高性能数据存储和处理技术日益增长的需求。磁性材料可以同时利用电荷和电子的自旋，这为新一代先进的“自旋电子”设备提供了一条途径，这些设备的性能超过了仅使用电子电荷所能实现的性能。电门控电荷传输的能力是电子革命的关键，但目前，还没有机制存在有效地在材料中门控磁性。该项目寻求对一种新的电磁控制机制的基本理解和实际应用，这种机制可以实现前所未有的控制水平，具有快速响应，低栅极电压和功率输入，以及多周期的鲁棒性。变革的方面是使用质子而不是电子来介导固体材料的磁性变化，通过使用小的施加电压将它们注入磁性薄膜或远离磁性薄膜。这种新的控制机制可以提供优越的功能，以实现未来的记忆、逻辑和其他基于旋转的技术，这些技术将对基础、技术和社会产生巨大的影响。该项目为本科生和研究生在关键的跨学科纳米技术方面提供了肥沃的训练场地，并将包括一个国际合作，为受资助的研究生提供国际科学接触。教育创新将在本科阶段通过以项目为中心的课程开发来实现。拓展和多样化活动将包括通过国家科学基金会教师研究经验计划接待高中教师，并在当地小学教室开发和提供“行动中的磁性”计划，用于科学，技术，工程和数学（STEM）的实践探索。技术：该计划的目标是通过在全固态薄膜异质结构中利用可逆的氢插入，使自旋电子器件中的电磁门和自旋输运成为一种新的手段。在与重金属Pt和Pd相邻的超薄铁磁薄膜中，逆对称的破坏和自旋轨道耦合会产生大量的现象，如垂直各向异性、手性和其他交换相互作用以及自旋轨道扭矩。这些相同的金属是众所周知的储氢材料，经历金属相和金属氢化物相之间的可逆转变，相应的结构和电子性能发生了实质性的变化。拟议研究的变革方面是利用由稀土氧化物/贵金属界面催化的环境气氛中的电化学水分解，作为固态质子泵，能够驱动H+离子通过栅极氧化物，进出靠近铁磁体的重金属。异质结构将被设计用于检查和优化关键磁性质的低压门控，评估反应和扩散动力学，识别和减轻设备故障模式，并将这些知识应用于可在动态磁波导和晶体中对自旋波进行电门控的示例性设备。这项提议的研究将建立一种革命性的新方法，使新的设备和基于自旋的结构成为可能，同时为探索当今纳米磁学中一些最重要的相互作用的起源提供了一个有力的旋钮。此外，该项目通过结合自旋电子学和固态离子学这两个传统上截然不同的学科，提供了新的跨学科见解，这将导致解决关键基础和技术挑战的协同方法。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

As conventional silicon-based electronics approaches fundamental physical limits, new materials and devices are urgently needed to meet the growing demand for low-power, high-performance data storage and processing technologies in today's information-based society. Magnetic materials, in which both the charge and the spin of the electron can be harnessed simultaneously, provide a path to enable a new generation of advanced 'spintronic' devices with capabilities beyond those that can be achieved using the electron charge alone. The ability to electrically gate charge transport was key to the electronics revolution, but at present, no mechanism exists to effectively gate magnetism in materials. This project seeks fundamental understanding and practical application of a new mechanism to control magnetism electrically that can enable an unprecedented level of control with fast response, low gate voltage and power input, and robustness over many cycles. The transformative aspect is the use of protons instead of electrons to mediate changes in magnetic properties in solid materials by injecting them towards and away from a magnetic thin film using a small applied voltage. This new control mechanism could deliver superior functionality to enable future memory, logic, and other spin-based technologies that would have tremendous fundamental, technological, and societal impact. The project provides a fertile training ground for undergraduate and graduate students in key interdisciplinary nanotechnologies, and will include an international collaboration that provides international scientific exposure for the supported graduate student. Educational innovation will be achieved through project-centric curriculum development at the undergraduate level. Outreach and diversity activities will include hosting high school teachers through the National Science Foundation Research Experience for Teachers program and by developing and delivering a 'Magnetism in Action' program at a local elementary school classroom for hands-on explorations in science, technology, engineering, and mathematics (STEM).Technical: The objective of the proposed program is to enable a new means to electrically gate magnetism and spin transport in spintronic devices by exploiting reversible hydrogen insertion in all-solid-state thin-film heterostructures. In ultrathin ferromagnetic films adjacent to a heavy metal like Pt and Pd, broken inversion symmetry and spin-orbit coupling give rise to a wealth of phenomena such as perpendicular anisotropy, chiral and other exchange interactions, and spin-orbit torques. These same metals are well-known hydrogen storage materials that undergo a reversible transition between metallic and metal-hydride phases with correspondingly substantial changes to structural and electronic properties. The transformative aspect of the proposed research is to harness electrochemical water splitting in the ambient atmosphere catalyzed by a rare-earth oxide/noble metal interface, to act as a solid-state proton pump capable of driving H+ ions through the gate oxide and into/out of the heavy-metal adjacent to a ferromagnet. Heterostructures will be designed to examine and optimize low-voltage gating of critical magnetic properties, to assess the reaction and diffusion kinetics, to identify and mitigate device failure modes, and to apply this knowledge to exemplary devices in which spin waves can be electrically gated in dynamic magnonic waveguides and crystals. The proposed research will establish a revolutionary new approach that will enable new devices and spin-based architectures, while providing a powerful knob to explore the origins of some of the most important interactions being studied in nanomagnetism today. The project moreover provides new interdisciplinary insights by combining spintronics with solid-state ionics, two traditionally distinct disciplines, which will lead to synergistic approaches to tackle key fundamental and technological challenges.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.