Exploring van der Waals heterostructure magnetic devices for high-efficiency and high-density memory

探索用于高效高密度存储器的范德华异质结构磁性器件

• 批准号: 2051450
• 负责人: Jing Shi
• 金额: $ 34.5万
• 依托单位: University of California-Riverside
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-06-01 至 2024-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2051450&HistoricalAwards=false
• 关键词: Exploring; van; der; Waals; heterostructure

This proposed research will explore van der Waals heterostructure-based magnetic devices capable of delivering highly efficient antidamping spin-orbit torque for switching perpendicular magnetization. Reducing energy dissipation for switching magnetic memory devices is increasingly challenging as the memory density scales up, which calls for innovative ways to greatly enhance the energy efficiency. Perpendicular magnetization with strong anisotropy is a requisite for the stability of high-density memory devices. The proposed research deals with a particular type of the van der Waals heterostructures which are composed of an atomically layered magnet with strong perpendicular magnetic anisotropy such as Fe3GeTe2 and another atomically layered Weyl semimetal with strong spin-momentum locking and low crystalline symmetry such as 1T’-WTe2. Unlike spin-orbit torques created by ordinary three-dimensional, high-symmetry materials, the unique antidamping torque generated by 1T’-WTe2 is expected to result in a much lower critical current density for switching the Fe3GeTe2 magnetization in this van der Waals heterostructure. Along with the atomically flat, chemically and magnetically sharp interface, the combination of these two materials provides unparalleled intrinsic and extrinsic properties suitable for future generations of high-density magnetic random access memory devices. The proposed research will provide excellent opportunities to educate graduate students across disciplines at PI’s institution, especially the underrepresented minority students by enrolling them in a newly developed elective course by the PI on van der Waals heterostructures and by training the student recruited for doing the cutting-edge research in this project.The objectives of this proposed research include (a) fabrication of the proposed van der Waals heterostructure nanoscale devices by exfoliation; (b) characterization of relevant physical properties including the perpendicular magnetic anisotropy constant, and saturation magnetization, and their temperature and thickness dependences, and tuning of magnetic properties such as magnetic anisotropy and Curie temperature; (c) experimental determination of critical switching current density and spin-orbit torque efficiency in the limits of few atomic layers in thickness and sub-100 nm in lateral dimensions; (d) optimization of van der Waals heterostructure materials, interfaces, and device geometry to maximize the energy efficiency. Successful exfoliation and nanoscale device fabrication of atomically thin magnetic materials are very recent scientific achievements and demonstration of the special out-of-plane spin-orbit torque in low-symmetry, atomically layered Weyl semimetal WTe2 was also accomplished recently. Integration of these newly discovered van der Waals materials to form unique heterostructures-based devices represents a bold endeavor that will lead to discoveries of new phenomena and advance the current understanding of materials science and physics of magnetic devices for high-efficiency and high-density memory.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.

这项拟议的研究将探索基于货车德华异质结构的磁性器件，能够提供高效的反阻尼自旋轨道转矩切换垂直磁化。随着存储器密度的增加，降低开关磁存储器器件的能量耗散越来越具有挑战性，这需要创新的方法来大大提高能量效率。 具有强各向异性的超导磁化强度是高密度存储器件稳定性的必要条件。拟议的研究涉及一种特殊类型的货车范德华异质结构，它是由一个原子层状磁铁与强垂直磁各向异性，如Fe 3GeTe 2和另一个原子层状Weyl半金属与强自旋动量锁定和低晶体对称性，如1 T '-WTe 2。不同于由普通三维高对称性材料产生的自旋-轨道扭矩，由1 T '-WTe 2产生的独特的反阻尼扭矩预计将导致用于在该货车德瓦尔斯异质结构中切换Fe 3GeTe 2磁化的低得多的临界电流密度。沿着原子级平坦、化学和磁性上尖锐的界面，这两种材料的组合提供了适合于未来几代高密度磁性随机存取存储器器件的无与伦比的内在和外在特性。拟议的研究将提供极好的机会，教育研究生跨学科在PI的机构，特别是代表性不足的少数民族学生，让他们参加PI新开发的关于货车范德华异质结构的选修课，并培训被招募进行该项目尖端研究的学生。通过剥离来制造所提出的货车范德华异质结构纳米级器件;（B）表征相关的物理性质，包括垂直磁各向异性常数和饱和磁化强度，以及它们的温度和厚度依赖性，以及调节磁性质，例如磁各向异性和居里温度;（c）在几个原子层的厚度和小于100 nm的横向尺寸的限制下，实验确定临界开关电流密度和自旋轨道扭矩效率;（d）优化货车德瓦尔斯异质结构材料、界面和器件几何形状，以最大化能量效率。原子级薄磁性材料的成功剥离和纳米级器件制造是最近的科学成就，并且最近还完成了低对称性，原子层状Weyl半金属WTe 2中特殊的面外自旋轨道扭矩的演示。整合这些新发现的货车德瓦尔斯材料以形成独特的基于异质结构的器件代表了一种大胆的奋进，这将导致新现象的发现，并推进当前对材料科学和磁性器件物理学的理解，以实现高效率和高性能。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的评估被认为是值得支持的。影响审查标准。