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技术相结合，为许多现代信息处理应用提供了令人兴奋的机会，可以构建能量、时间和尺寸都大大降低的设备。这开创了新兴的自旋电子学领域。自旋电子器件最近作为特别有前途的候选者出现的两个应用是：(a)处理从人工智能到密码学到量子模拟等领域常见的大量概率数据，以及(b)在没有焦耳加热的情况下在芯片上传输信息。然而，到目前为止，主要用于制造此类器件的磁性材料存在不必要的杂散磁相互作用、缓慢的自旋动力学和/或在电和磁畴之间传递信息的效率差。这限制了自旋电子器件的使用范围，需要寻找替代材料平台来构建此类器件。该项目的目标是通过将理论与原理验证实验相结合，研究一种称为手性反铁磁体的新型磁铁，以解决这一挑战。手性反铁磁体表现出组成电子自旋的非共线和手性排列，从而产生八极子磁序。这种磁序同时提供高速运行、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子的概率比特和超流体启发的手性反铁磁体自旋导管。这些设计有可能实现运行概率算法的能量降低2-3个数量级，并实现超越最先进的自旋信息长距离传输。在整个项目中，首席研究员还将为本科生和研究生提供从磁学到非常规计算再到量子传感等各种主题的培训。这将增强美国在微电子和量子信息科学交叉领域的劳动力。本研究旨在为利用手性反铁磁体中的八极子磁序构建新型自旋电子器件奠定基础知识。该项目的重点是具有负手性的手性反铁磁体，其中八极矩在一个简单的平面内表现出大角度的非线性动力学。两种互补的几何结构——纳米磁体和纳米线——将分别用于制造p位和超流体激发的自旋器件。由于手性反铁磁体中的磁相互作用与自旋之间的强交换场之间的有趣相互作用，新的基于八极矩的p位具有低八极子涨落障碍和高速八极子动力学。与目前的p位相比，这有望使每秒的翻转次数提高2-3个数量级，这是控制运行各种概率算法所需的能量和/或时间的关键数字。另一方面，提出的手性反铁磁体中基于八极子的自旋管道的探索是独一无二的，因为它通过展示在室温下的单个平台中结合了以下特性：(i)有效注入自旋以启动八极子的大角度非线性动力学的能力，（ii）缺乏杂散相互作用，以及（iii）低阻尼。这为解决室温下超流体激发的长距离自旋输运的长期挑战提供了一条有希望的途径。为了探索所提出的设备，首席研究员将在热驱动和自旋轨道驱动的存在下，在从原子到电路的宽长度尺度上开发八极矩随机动力学的实验基准理论。实验基准测试将利用自旋量子比特探针和电学表征的使用。除了实现所提出的设备的潜力之外，该研究预计将产生在反铁磁自旋电子学领域开发手性反铁磁体所需的基本理解和模型。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。

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.