Collaborative Research: Correlating Device Performance and Interfacial Properties for Weyl Spintronics

这项拨款支持研究理解新的机制，通过电流可以用来切换数据处理和存储设备中薄磁层的磁取向。利用电流脉冲来改变磁性是各种电子和自旋电子设备工作原理的核心。然而，需要新的材料系统来降低磁开关所需的功耗，并实现未来的设备缩放。该奖项支持识别被称为Weyl半金属的量子材料的基础研究，这些材料可以显着提高电流感应磁开关的效率。该项目将描述用于磁性器件的各种Weyl半金属，重点是了解Weyl半金属和磁性层之间的界面特性如何影响开关指标。该项目还将确定如何使用Weyl半金属来实现垂直磁铁的开关，以促进新兴设备概念。关于新量子材料如何降低电子和磁性设备功耗的见解可能会导致电子和计算设备的新进步，提供广泛的社会效益。该项目使学生的研究训练成为可能，通过为他们提供为技术部门做出贡献所需的实验技能，将有助于促进美国的经济利益。该合作项目将通过一系列研究活动为低功率自旋电子器件奠定基础，旨在提供对Weyl半金属产生的自旋轨道扭矩的详细了解。电荷到自旋转换过程将在Weyl半金属和铁磁金属之间的一系列界面上进行彻底的表征，以量化扭矩效率。这些相同结构的界面特性将使用共振x射线反射率来表征，这种技术允许元素浓度和磁化强度作为界面深度的函数来确定。自旋轨道转矩效率与界面的组成和磁性之间的相关性将阐明本征（Weyl物理）和本征（界面的非理想性）对转矩的贡献。这些活动将产生对使用工业相关沉积工艺制造的基于器件的结构中真实界面上的自旋轨道扭矩的透彻理解。该研究还将确定新的自旋轨道扭矩，包括那些与面外自旋极化相关的扭矩，这是由Weyl半金属的独特特性实现的，并量化与非易失性磁存储器件和热驱动随机振荡器相关的扭矩指标，其中自由磁层的磁化是通过自旋轨道扭矩控制的。通过这些研究活动，该项目将推动在新兴电子和自旋电子器件体系结构中使用Weyl半金属的进展。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。

This grant supports research into understanding new mechanisms by which electrical currents can be used to switch the magnetic orientation of thin magnetic layers in devices for data processing and storage. The use of current pulses to alter magnetism is central to the operating principles of a variety of electronic and spintronic devices. However, new materials systems are needed to reduce the power consumption required for magnetic switching and to enable future device scaling. This award supports fundamental research to identify quantum materials known as Weyl semimetals that enable significant improvements in the efficiency of current-induced magnetic switching. The project will characterize a variety of Weyl semimetals for use in magnetic devices with emphasis on understanding how the switching metrics are influenced by the interfacial properties between the Weyl semimetal and the magnetic layer. The project will also identify how Weyl semimetals can be used to enable switching of perpendicular magnets to facilitate emerging device concepts. The insights into how new quantum materials can reduce power consumption in electronic and magnetic devices may lead to new advances in electronics and computing devices, providing broad societal benefit. The students’ research training enabled by this project will serve to advance the U.S. economic interests by providing them with the experimental skill set needed to contribute to the technological sector.This collaborative project will lay the groundwork for low-power spintronic devices through a series of research activities aimed at providing a detailed understanding of spin-orbit torques generated by Weyl semimetals. The charge-to-spin conversion process will be thoroughly characterized at a series of interfaces between Weyl semimetals and ferromagnetic metals to quantify torque efficiencies. The interfacial properties of these same structures will be characterized using resonant x-ray reflectivity, a technique that allows for both the elemental concentration and magnetization to be determined as a function of depth across the interfaces. The correlations between spin-orbit torque efficiency and the composition and magnetic properties of the interfaces will elucidate the roles of intrinsic (Weyl physics) and extrinsic (non-idealities at the interfaces) contributions to the torques. These activities will yield a thorough understanding of spin-orbit torques across real interfaces in device-based structures fabricated using industry-relevant deposition processes. The research will also identify novel spin-orbit torques, including those associated with an out-of-plane spin polarization, enabled by the unique properties of Weyl semimetals and quantify torque metrics relevant for non-volatile magnetic memory devices and thermally driven stochastic oscillators, where the magnetization of the free magnetic layer is controlled via spin-orbit torques. Through these research activities, this project will advance progress toward employing Weyl semimetals in emerging electronic and spintronic device architectures.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.