Spin Current Phenomena in Non-Collinear Antiferromagnets:From Fundamental Physics to Device Concepts

非共线反铁磁体中的自旋流现象：从基础物理到器件概念

• 批准号: 2408972
• 负责人: Mingzhong Wu
• 金额: $ 36.8万
• 依托单位: Northeastern University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-10-01 至 2024-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2408972&HistoricalAwards=false
• 关键词: Spin; Current; Phenomena; Non; Collinear

Recent years have witnessed a rapidly growing interest in antiferromagnetic spintronics. Up to now, however, most of the research has focused on collinear antiferromagnetic systems. Spin current phenomena in non-collinear antiferromagnetic systems remain largely unexplored. Very recent theoretical work has uncovered new phenomena in non-collinear antiferromagnets Mn3X, where X is Sn, Ga, or Ge. These include an unusual spin Hall effect, a strong spin Nernst effect, and electric manipulation of antiferromagnetic ordering. The heart of this program is the timely experimental elucidation of these phenomena and their use in prototype devices. The studies will largely promote the understanding of spin-related phenomena in non-colinear antiferromagnets and will thereby significantly advance the research field of antiferromagnetic spintronics. From a technological perspective, the proposed research will have significant implications for the future development of magnetic memory, spin-torque nano-oscillators, and spin-wave logic and will therefore have a major impact on future advanced electronic systems. Two undergraduate students and two graduate students per year will participate in film growth, nanofabrication, electrical transport and high-frequency measurements, and data analysis. Outreach to high schools will be accomplished through the Colorado State University 'Little Shop of Physics' and the 'summer Research and Engineering Apprenticeship" Programs.The program consists of three main research thrusts. Thrust I will focus on a rather unusual spin Hall effect in Mn3Sn. A normal spin Hall effect can convert a longitudinal charge current to a transverse spin current whose polarization is orthogonal to the spin flow direction. In stark contrast, the transverse spin current produced by the unusual spin Hall effect has a polarization that is along the spin flow direction. This unusual phenomenon will be demonstrated through two distinct approaches. Further, the effect will be used to induce magnetization switching, drive magnetization precession, and excite spin waves in ferromagnetic thin films with perpendicular anisotropy. None of these effects can be achieved, in principle, with spin currents produced by the normal spin Hall effect, the Rashba effect, or topological surface states. Thrust II will focus on the spin Nernst effect, a process in which one uses a thermal gradient to produce pure spin currents. Recent experiments have revealed this effect in Pt. Very recent theoretical work indicates that the effect can also occur in Mn3X and can be significantly stronger than in Pt. Thrust II will elucidate these predicted strong spin Nernst effect for Mn3X films. It is also planned to use this effect for spin-orbit torque-induced magnetization switching in ferromagnetic films with perpendicular anisotropy. Thrust III will focus on the control of antiferromagnetic ordering in Mn3X. Work is planned to manipulate antiferromagnetic states using damping-like and field-like spin-orbit torques and move domain walls through spin transfer torque. While theory suggests that such ordering control is feasible, this has not yet been demonstrated experimentally.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.

近年来，人们对抗磁性旋转的兴趣迅速增长。 然而，到目前为止，大多数研究都集中在共线抗磁磁系统上。 非共线抗铁磁系统中的自旋电流现象在很大程度上尚未探索。 最近的理论工作已经发现了非共线性抗铁磁铁MN3X中的新现象，其中X是SN，GA或GE。 其中包括异常的自旋效果，强烈的旋转效果以及对抗铁磁秩序的电动操纵。 该程序的核心是对这些现象的及时实验阐明及其在原型设备中的使用。 这项研究将在很大程度上促进对非连续性抗铁磁铁中自旋相关现象的理解，从而显着提高抗磁性旋转的研究领域。从技术的角度来看，拟议的研究将对磁记忆，旋转旋转纳米振荡器和自旋波逻辑的未来发展产生重大影响，因此将对未来的先进电子系统产生重大影响。 每年两名本科生和两名研究生将参加电影的增长，纳米制作，电气运输和高频测量以及数据分析。将通过科罗拉多州立大学的“小物理学”和“夏季研究和工程学徒制”计划来实现与高中的宣传计划。该计划由三个主要的研究推力组成。我将专注于MN3SN中相当不寻常的自旋霍尔的效应。正常的旋转霍尔可以将较长的电荷转化为横向旋转的电流或跨度旋转的旋转旋转的旋转旋转的旋转旋转的旋转，以使旋转趋于旋转旋转旋转的旋转量。由异常的旋转方向产生的旋转效果将通过两种不同的方法来证明这种异常现象。 RASHBA效应或拓扑表面状态。 推力II将集中在旋转的NernST效果上，其中人们使用热梯度产生纯自旋电流。 最近的实验在PT中揭示了这种影响。 最近的理论工作表明，这种影响也可能发生在MN3X中，并且可能比PT明显强大。 推力II将阐明这些预测的MN3X膜的强旋转效果。 还计划将这种效果用于垂直磁性膜中的自旋轨道扭矩诱导的磁化切换。 推力III将集中于MN3X中抗铁磁秩序的控制。 计划使用类似阻尼和野外的自旋轨道扭矩来操纵抗铁磁状态，并通过自旋传输扭矩移动域壁。尽管理论表明这种秩序控制是可行的，但尚未通过实验证明这一点。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子优点和更广泛影响的评估标准通过评估来支持的。