Magnetic Octupole Based Next-generation Spintronic Devices in XY-like Chiral Antiferromagnets

将磁序与当今基于电荷的电子学相结合，为许多现代信息处理应用提供了令人兴奋的机会，可以构建具有数量级减少的能量、时间和尺寸的设备。这引发了自旋电子学的蓬勃发展。自旋电子器件最近成为特别有前途的候选者的两个应用是：（a）处理从人工智能到密码学到量子仿真等领域中常见的大量概率数据，以及（B）在不存在焦耳热的情况下在芯片上传输信息。然而，迄今为止主要用于制造这种器件的磁性材料遭受不希望的杂散磁相互作用、慢自旋动力学和/或在电域和磁畴之间转换信息的效率差。这限制了自旋电子器件的范围，并需要寻找替代材料平台来构建这种器件。该项目的目标是通过将理论与原理验证实验相结合，研究一类称为手性反铁磁体的新磁体，以应对这一挑战。手征反铁磁体的电子自旋呈现非共线的手征排列，从而产生八极磁序。这种磁序同时提供了高速操作、无杂散相互作用和高转导效率。特别是，首席研究员将研究和设计新的基于八极的概率位和超流体启发的自旋管道在手性反铁磁体。这些设计有可能实现2-3个数量级的能量减少，分别用于运行概率算法和实现超过最先进的自旋信息的长距离传输。在整个项目中，首席研究员还将为不同的本科生和研究生提供培训，主题从磁性到非常规计算再到量子传感。这将增强美国在微电子学和量子信息科学交叉领域的劳动力。拟议的研究旨在建立基础知识，以利用手性反铁磁物质中的八极磁序来构建新型自旋电子器件。该项目的重点是手征反铁磁体与负手征，八极矩表现出大角度的非线性动力学在一个简单的平面。两种互补的几何形状-纳米磁体和纳米线-将被探索分别创建p位和超流体启发的自旋设备。由于手征反铁磁体中的磁相互作用和自旋之间的强交换场之间的有趣的相互作用，新的基于八极矩的p比特表现出对八极波动和高速八极动力学的低势垒。这保证了每秒翻转比当前的p比特有2-3个数量级的增强，这是一个关键的品质因数，它决定了达到运行各种概率算法的解决方案所需的能量和/或时间。另一方面，所提出的在手性反铁磁体中探索基于八极的自旋管道的探索是独特的，因为它通过证明在室温下在单个平台中结合了以下性质：（i）有效地注入自旋以启动八极的大角度非线性动力学的能力，（ii）不存在杂散相互作用，以及（iii）低阻尼。这为解决长期存在的挑战提供了一个有希望的途径，即在室温下实现超流体驱动的长距离自旋传输。为了探索所提出的设备，主要研究人员将在热和自旋轨道驱动器的存在下，开发从原子到电路的宽尺度八极矩随机动力学的实验基准理论。实验基准将利用自旋量子位探针和电气特性。除了潜在的，使拟议的设备，该研究预计将产生基本的理解和模型，需要利用手性反铁磁在反铁磁自旋电子学领域。这一奖项反映了NSF的法定使命，并已被认为是值得通过评估使用基金会的智力价值和更广泛的影响审查标准的支持。

Integrating magnetic order with present-day charge-based electronics offers exciting opportunities to construct devices with orders of magnitude reduced energy, time, and size for many modern information processing applications. This has initiated the burgeoning field of spintronics. Two applications where spintronic devices have recently emerged as particularly promising candidates are: (a) processing large amounts of probabilistic data commonly found in fields ranging from artificial intelligence to cryptography to quantum emulation, and (b) transporting information on chips without the presence of Joule heating. However, the magnetic materials predominantly used for fabricating such devices thus far suffer from unwanted stray magnetic interactions, slow spin dynamics, and/or poor efficiency in transducing information between the electrical and magnetic domains. This has limited the scope of spintronic devices and created a need to search for alternative material platforms to construct such devices. The goal of this project is to study by combining theory with proof-of-principle experiments, a new class of magnets called chiral antiferromagnets, in order to address this challenge. Chiral antiferromagnets exhibit a non-collinear and chiral arrangement of constituent electronic spins, which gives rise to octupole magnetic order. This magnetic order simultaneously offers high-speed operation, absence of stray interactions, and high transduction efficiencies. In particular, the principal investigator will study and design novel octupole-based probabilistic bits and superfluid-inspired spin conduits in chiral antiferromagnets. These designs have the potential to achieve a 2-3 orders of magnitude reduction in energy for running probabilistic algorithms and enabling beyond state-of-the-art long-distance transfer of spin information, respectively. Throughout this project, the principal investigator will also provide training to a diverse set of undergraduate and graduate students in topics ranging from magnetism to unconventional computing to quantum sensing. This will enhance the United States' workforce at the intersection of microelectronics and quantum information science.The proposed research aims to establish foundational knowledge for exploiting the octupole magnetic order in chiral antiferromagnets to construct novel spintronic devices. The project focuses on chiral antiferromagnets with negative chirality, where the octupole moments exhibit large-angle nonlinear dynamics within an easy plane. Two complementary geometries - nanomagnets and nanowires - will be explored to create p-bits and superfluid-inspired spin devices, respectively. Due to the interesting interplay between magnetic interactions in chiral antiferromagnets and strong exchange fields between spins, the new octupole moment-based p-bits exhibit low barriers to octupole fluctuations and high-speed octupole dynamics. This promises a 2-3 orders of magnitude enhancement in flips per second over present-day p-bits, which is a key figure of merit that governs the energy and/or time required to reach the solution for running a wide variety of probabilistic algorithms. On the other hand, the proposed exploration of octupole-based spin conduits in chiral antiferromagnets is unique in that it combines the following properties in a single platform at room temperature by demonstrating: (i) capability to efficiently inject spins to initiate large-angle non-linear dynamics of octupoles, (ii) absence of stray interactions, and (iii) low damping. This provides a promising avenue to solve the long-standing challenge of superfluid-inspired long-distance transport of spin at room temperature. To explore the proposed devices, the principal investigator will develop experimentally benchmarked theories of the stochastic dynamics of octupole moments across wide length scales, ranging from atoms to circuits, in the presence of thermal and spin-orbit drives. The experimental benchmarking will leverage the use of spin qubit probes and electrical characterization. Beyond the potential to enable the proposed devices, the study is expected to generate fundamental understanding and models needed to exploit chiral antiferromagnets in the field of antiferromagnetic spintronics.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.