CAREER: Next-generation Logic, Memory, and Agile Microwave Devices Enabled by Spin Phenomena in Emergent Quantum Materials

拟议的研究将通过创新影响社会，以实现新的设备技术。将实施一项培训下一代研究人员和增加代表性不足群体参与的计划。一个多年的指导计划，这将提供研究经验的本科生在主要研究者的实验室从少数民族服务机构将通过这一研究计划建立。将制定面向公众的外联方案，并将针对宾夕法尼亚州西南部地区代表性不足的少数民族的K-12学生。与此同时，还将开发一门通过动手实验教授量子物理学基本概念的课程。本课程将提供教育，为美国新兴产业培养下一代量子劳动力。新型量子材料中的新兴现象是实现计算，数据存储和高频电子设备变革的关键。对于磁存储器件，所提出的研究将使一种备受追捧的两端自旋轨道扭矩磁存储器件成为可能，以实现节能和超紧凑的数据存储。为了构建具有行业竞争力的磁存储器设备，需要一个占用空间小的硬件节点来实现密集的存储元件网络。然而，到目前为止，在本领域中考虑的自旋轨道扭矩驱动的磁存储器器件具有三个端子，其中磁隧道结集成在自旋源材料的顶部上以通过隧道磁阻效应读取状态。 自旋-轨道扭矩驱动的磁存储器器件被设想为是高度能量有效的，因为由自旋霍尔效应现象引起的自旋电流在磁化操纵方面比基于磁隧道结的器件中使用的自旋极化电流更有效。然而，一个自旋轨道扭矩为基础的双端设备一直严重缺失。本研究计划将展示一个原型的自旋-轨道扭矩为基础的双端设备的磁存储器的应用中，磁状态的读取使用一种新的磁阻由于面外自旋电流在Weyl半金属。此外，二维磁体中的磁相互作用的电调谐可以实现灵活的微波器件，例如可调谐带通滤波器。基于磁性材料中自旋波激发的微波滤波器具有实现紧凑、平面和频率捷变等功能的潜力。然而，实现自旋波激励的电可调谐性（其决定基于磁体的带通滤波器的通过频率和抑制频率）对于微波器件是高度期望的，但它仍然具有挑战性。本研究计画将探讨及示范二维磁铁之闸极电压调整，以制作电场可调带通滤波器装置之原型。一个研究计划，旨在实验演示的变革设备功能的下一代存储器和高频设备使用新兴自旋现象外尔半金属和二维磁铁将被追求。 该研究计划的具体科学目标有两个：（1）展示一种基于双端自旋轨道矩的磁存储单元，其中信息存储在具有垂直磁各向异性的铁磁体的磁状态中，磁状态通过自旋轨道矩现象写入，状态通过Weyl半金属中倾斜自旋电流产生的新型磁阻读取;（2）基于二维磁体的电场可调谐带通滤波器。将探索磁各向异性的电场可调谐性以调谐磁体的磁共振，这是频率捷变带通滤波器的关键特性，因为电场的应用将移动共振频率的位置以建立所提出的微波装置的通带和阻带。该奖项反映了NSF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。

The proposed research will impact society through the innovation to realize new device technologies. A program to train next-generation researchers and increase underrepresented groups’ participation will be pursued. A multi-year mentoring program, which will provide research experience for undergraduate students in the principal investigator’s lab from minority serving institutions will be established through this research program. Outreach programs for the public will be developed and will be targeted towards K-12 students belonging to underrepresented minorities in southwestern Pennsylvania area. In parallel, a course to teach fundamental concepts of quantum physics through hands-on experiments will be developed. This course will provide education to produce the next-generation quantum workforce for emergent industries in the United States.Emergent phenomena in novel quantum materials are key to enable transformative devices for computing, data storage, and high-frequency electronics. For magnetic memory devices, the proposed research will enable a much sought after two-terminal spin-orbit torque magnetic memory device for energy efficient and ultra-compact data storage. To build an industry competitive magnetic memory device, a small footprint hardware node is desired to implement a dense network of storage elements. However, spin-orbit torque driven magnetic memory devices considered so far in the field have three terminals, wherein a magnetic tunnel junction is integrated on top of spin-source material to read the state through tunnel-magnetoresistance effect. The spin-orbit torque driven magnetic memory devices are envisioned to be highly energy-efficient because spin current induced by spin Hall effect phenomena is more efficient at magnetization manipulation than spin-polarized current used in magnetic tunnel junction-based devices. However, a spin-orbit torque based two-terminal device has been critically missing. This research program will demonstrate a prototype spin-orbit torque based two-terminal device for magnetic memory applications in which the magnetic state is read using a new kind of magnetoresistance owing to out-of-plane spin current in Weyl semimetals. Additionally, the electrical tuning of magnetic interactions in two-dimensional magnets can enable agile microwave devices, such as tunable band-pass filters. Microwave filters based on spin-wave excitations in magnetic materials have the potential to realize functionalities such as compactness, planar, and frequency-agility. However, achieving an electrical turnability of spin-wave excitations, which decides the pass and rejection frequency of a magnet based band-pass filter, is highly desired for microwave devices but it remains challenging. This research program will explore and demonstrate gate voltage tuning of magnetic anisotropy in two-dimensional magnets for prototyping electric-field tunable band-pass filter devices. A research program aimed at experimental demonstration of transformative device functionalities for next-generation memory and high-frequency devices using emergent spin-phenomena in Weyl semimetals and two-dimensional magnets will be pursued. The specific scientific goals of this research program are twofold: (1) A two-terminal spin-orbit torque based magnetic memory unit cell will be demonstrated, wherein the information is stored in the magnetic state of ferromagnet with perpendicular magnetic anisotropy, the magnetic state is written by the spin-orbit torque phenomena, and the state is read through a new type of magnetoresistance owing to tilted spin current in Weyl semimetals; (2) An electric-field tunable band-pass filters based on two-dimensional magnets will be demonstrated. The electric field tunability of magnetic anisotropy to tune the magnetic resonance of a magnet will be explored, which is the key characteristic of a frequency agile band-pass filter because the application of electrical field will shift the location of resonance frequency to set up the pass and rejection band of the proposed microwave device. For proposed band-pass filters, insertion loss, pass-filter center frequency, operational bandwidth, and other device parameters will be characterized.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.