CAREER: Designing and Probing Emergent Phases with Tunable Magnons in Graphene

摘要：磁振子是磁性材料中具有量子力学性质的波状物体，其特征与电子完全不同。利用磁振子为创造自然界中没有的合成物质和开发具有前所未有功能的下一代量子器件提供了一条有趣的途径。虽然电子的性质已经得到了深入的研究，但对固体中的磁振子及其集体行为的研究仍然非常有限。探索这一方向的一个有前途的可调平台是石墨烯——一层碳原子——放置在强磁场中，在那里可以有效地发射和检测磁振子。该项目的主要目标是探索利用磁振子作为构建块来设计可能的量子现象，并研究利用磁振子探测原子薄材料磁性的可行性。该项目的成功有望推进基础量子科学的前沿，并为超低功耗信息设备等未来量子技术提供创新途径。该项目还将材料教育与不断增长的社会对量子技术的需求联系起来，通过研究为高中生、本科生和研究生提供教育和推广计划。技术摘要：对电荷中性玻色子的相关态和拓扑态的探索，为推进我们对自然界中未发现的物质的涌现相的理解，以及为量子技术打开新的机遇，提供了一条引人注目的途径。磁振子，也被称为自旋波，在单层石墨烯的量子霍尔铁磁状态下，由于其非凡的可调性、长寿命、全电产生和探测方案以及对磁环境的显著敏感性，最近成为设计和探测玻色子涌现相的通用固态平台。然而，我们对磁振子之间的相互作用及其与周围环境的耦合的了解仍然非常有限。该项目旨在通过实验解决这些关键问题，以促进未来磁振子涌现相和磁振子自旋探针的理论分析和实验发展。这项研究是利用范德华组装和莫尔粒子的最新进展，以及量子电子输运和扫描探针显微镜技术的创造性结合来提取超高质量石墨烯异质结构中磁振子的输运和热力学性质而成为可能的。最终，该项目为固体中玻色子的相关相和拓扑相的设计、构建、表征和操作提供了一条新的途径，并为揭示二维材料中的相关现象建立了一种新的、通用的、有效的工具。此外，本项目通过为本科生、研究生和高中教师提供量子科学研究和培训机会，以及开设二维量子材料新课程，具有更广泛的影响。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。

Non-technical abstractMagnons are quantum mechanical, wave-like objects in magnetic materials that display fundamentally different characteristics than electrons. Harnessing magnons presents an intriguing avenue for creating synthetic matter not found in nature and developing next-generation quantum devices with unprecedented functionalities. While the properties of electrons have been intensively studied, the investigation of magnons and their collective behavior in solids remains extremely limited. A promising and tunable platform to explore this direction is graphene - a sheet of carbon atoms - placed in a strong magnetic field, where magnons can be efficiently launched and detected. The primary goal of this project is to explore the possible quantum phenomena that can be engineered by using magnons as building blocks and to investigate the feasibility of utilizing magnons to probe the magnetic properties of atomically thin materials. The success of this project promises to advance the frontier of fundamental quantum science and enable innovative pathways to future quantum technologies such as ultra-low-power information devices. This project also connects materials education with the growing societal demand for quantum technology through research-informed education and outreach programs for high school, undergraduate, and graduate students.Technical AbstractThe exploration of correlated and topological states of charge-neutral bosons presents a compelling avenue for advancing our understanding of emergent phases of matter not found in nature and unlocking new opportunities in quantum technology. Magnons, also known as spin waves, in the quantum Hall ferromagnetic state of monolayer graphene, have recently emerged as a versatile solid-state platform for designing and probing emergent phases of bosons, owing to their extraordinary tunability, long lifetime, all-electrical generation and detection scheme and their remarkable sensitivity to the magnetic environment. However, our knowledge about the interaction between magnons and their coupling to the surrounding environments remains extremely limited. The project aims to experimentally address these key questions to facilitate future theoretical analysis and experimental development of emergent phases of magnons and a magnon-enabled spin probe. This investigation is made possible by leveraging recent advances in van der Waals assembly and moiré quantum matter, along with a creative combination of quantum electronic transport and scanning probe microscopy techniques to extract transport and thermodynamics properties of magnons in ultra-high-quality graphene heterostructures. Ultimately, this project provides a new pathway for the design, construction, characterization, and manipulation of correlated and topological phases of bosons in solids and establishes a new, generic, and effective tool for unraveling correlated phenomena in two-dimensional materials. In addition, this project has a broader impact through research and training opportunities in quantum science for undergraduates, graduate students, and high school teachers, and a new course on two-dimensional quantum materials.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.