RII Track-4:NSF: Resistively-Detected Electron Spin Resonance in Multilayer Graphene

该研究基础设施改善轨道4 EPSCoR研究人员项目将为布朗大学的助理教授提供奖学金，并为博士后提供培训。自旋是电子的固有特性，是理解量子材料低温电子特性的关键。例如，当许多电子的自旋排列在一个首选方向时，磁性就会发生，而超导的本质则关键取决于底层电子对的自旋配置。在由两到三层碳原子组成的原子薄材料中，降维增强了库仑相关（描述了由于它们的库仑排斥而导致的电子空间位置之间的相关性），这进一步放大了电子自旋的作用。本项目旨在开发一种实验方法来直接探测这些二维材料中电子自旋的构型。这项提议利用了美国国家高磁场实验室最先进的用户设施。通过让学生和研究人员接触国家实验室的前沿研究，研究和推广计划激励和教育未来的科学家和工程师在量子科学和量子材料研究领域担任领导角色和先驱创新。该研究项目还旨在在罗德岛建立一个用户计划，该计划有望通过为不同水平的学生提供研究和实习职位，对罗德岛缺乏量子的劳动力的培训产生广泛的影响。强相关二维材料的低温相图包含许多奇异的量子相，如超导和铁磁性。要了解这些新兴现象背后的微观起源，关键是首先要确定电子自旋的确切构型。然而，缺乏可行的实验方法给揭示自旋自由度的顺序带来了障碍，这给旨在更好地理解二维材料（如多层石墨烯）中电子态性质的研究工作带来了主要挑战之一。在本提案中，PI提出了一种能够直接探测电子自旋性质的实验方法的新范式，该方法利用电阻检测电子自旋共振测量。此外，PI将研究自发旋转对称破缺的库仑驱动过程。最近的实验进展表明，自发旋转对称破缺可以基于角分辨非互易输运测量来表征。在这些进展的基础上，该研究项目将研究多层石墨烯中的电子自旋配置，如Bernal堆叠双层石墨烯和魔角扭曲三层石墨烯，以及其与自发旋转对称性破断过程的联系。该项目的结果将通过提供对由强相关性和非平凡拓扑之间相互作用稳定的电子顺序的性质的新见解，产生深远的影响。拟议的项目将利用国家高磁场实验室（NHMFL）最先进的用户设施，在那里有能力的工作人员科学家提供强有力的技术支持。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。

This Research Infrastructure Improvement Track-4 EPSCoR Research Fellows project will provide a fellowship to an Assistant Professor and training for a postdoctoral fellow at Brown University. Spin is an intrinsic property of electrons, which is key to understanding electronic properties of quantum materials at low temperatures. For instance, magnetism occurs when spins of many electrons align in a preferred direction, whereas the nature of superconductivity is crucially dependent on the spin configuration of the underlying electron pairs. In atomically thin materials consisting of two to three layers of carbon atoms, the reduced dimension enhances Coulomb correlation (describes the correlation between the spatial position of electrons due to their Coulomb repulsion), which further amplifies the role of electronic spin. This project aims to develop an experimental method to directly probe the configuration of electron spins in these 2D materials. The proposed effort takes advantage of the state-of-the-art user facility at the National High Magnetic Field Lab. By exposing students and researchers to cutting-edge research in the national lab, the research and outreach program inspires and educates future scientists and engineers to take on leadership roles and pioneer innovations in the field of quantum science and quantum material research. The research project also aims to establish a user program located in Rhode Island, which promises to have wide wide-ranging impact on training Rhode Island’s quantum-deficient workforce by providing research and intern positions for different levels of students.The low-temperature phase diagram of strongly correlated 2D materials hosts many exotic quantum phases, such as superconductivity and ferromagnetism. To understand the microscopic origin underlying these emergent phenomena, it is key to first identify the exact configuration of electronic spin. However, the lack of viable experimental methods presents a hurdle to uncovering the order in the spin degrees of freedom, which gives rise to one of the main challenges for research efforts aiming to better understand the nature of electronic states in 2D materials such as multilayer graphene. In this proposal, the PI puts forth a new paradigm of experimental methods that are capable of directly probing the nature of electronic spin, which utilizes resistively detected electron spin resonance measurement. Moreover, The PI will investigate the Coulomb-driven process of spontaneous rotational symmetry breaking. Recent experimental progress demonstrated that spontaneous rotational symmetry breaking can be characterized based on angle-resolved nonreciprocal transport measurement. Building on these developments, the proposed research project will investigate the electronic spin configuration in multilayer graphene, such as Bernal stacked bilayer graphene and magic-angle twisted trilayer graphene, along with its connection to the process of spontaneous rotational symmetry breaking. Results from this project will have a far-reaching impact by providing new insights into the nature of electronic orders stabilized by the interplay between strong correlation and nontrivial topology. The proposed project will utilize the state-of-the-art user facility at the National High Magnetic Field Lab (NHMFL), where capable staff scientists provide strong technical support.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.