MRI: Acquisition of A Low-Temperature Scanning Tunneling Microscope For Advanced Surface Analysis

卡内基梅隆大学的五位教授将通过NSF MRI计划获得低温扫描隧道显微镜（LT-STM）。该仪器允许在低温和高磁场下绘制表面上的原子排列。研究将集中在“二维（2D）材料”上，即只有一层原子厚的材料。在这样的材料中，电子被限制在单个原子层内移动，从而获得了规则三维材料所不具备的某些新特性。此外，在拟议的工作中，不同类型的2D层将堆叠在另一个之上。这种二维材料的组合具有与常规三维材料不同的特性。例如，发现电子在2D材料中的移动速度比在3D材料中快得多，从而允许制造新型电子设备（用于速度更快且需要更少功率的计算机）。此外，2D中电子的磁性与3D中发生的任何事情都不同，这也有可能成为新型计算设备。LT-STM不仅会对卡内基梅隆大学的研究人员产生影响，而且会对匹兹堡量子研究所产生更广泛的影响，该研究所包括来自匹兹堡大学、CMU和Dusquesne大学的约50名教师。拟议的LT-STM将作为一个强大的表征工具，研究所的成员进行的研究项目。卡内基梅隆大学（CMU）的五名研究人员提出要获得一种低温扫描隧道显微镜（LT-STM），包括磁场能力。将研究二维（2D）材料和异质结构。只有一个或几个原子层厚的2D材料通过从块状晶体“剥离”形成，即从块状晶体剥离一个或几个原子层并将这些层沉积在合适的惰性基底上。这样的二维层表现出一系列奇异的特性，包括无质量费米子，拓扑保护态，超导性和铁磁相，所有这些都将在LT-STM中进行探测。此外，垂直异质结构将通过将一个原子层转移到另一个原子层的顶部来形成; CMU拥有进行这种制造的最先进设施。在这种异质结构中，材料的性质可以被控制，因为一层与另一层相邻的存在产生了与单个层不同的集体行为。所有的研究人员都积极指导研究生和本科生的研究，拟议的LT-STM仪器将显着提高这些活动。此外，该设施将影响目前在CMU进行的与研究人员的实验工作有关的理论研究。该仪器预计也将对CMU的“节能计算2D材料和设备中心”产生重大影响，其中四名PI是该中心的成员。LT-STM的操作计划已经制定，将允许外部用户访问它。其中四名研究人员是“匹兹堡量子研究所”的成员，该研究所包括来自匹兹堡大学、CMU和杜斯肯大学的约50名教师。拟议的LT-STM将作为一个强大的表征工具，研究所的成员进行的研究项目。

Non-technical AbstractFive professors at Carnegie Mellon University will acquire a low-temperature scanning tunneling microscope (LT-STM), through the NSF MRI program. This instrument permits the mapping of atomic arrangements on surfaces, at low temperatures and under high magnetic fields. Studies will focus on "two-dimensional (2D) materials", that is, materials that are only one layer of atoms thick. In such materials, electrons are confined to move within the single atomic layer, and they thereby acquire certain novel properties that do not occur for regular, three-dimensional materials. Additionally, in the proposed work, different types of 2D layers will be stacked on top of another. Such combinations of 2D materials possess properties that, again, are unlike any found in regular, three-dimensional materials. For example, electrons are found to move much faster in 2D materials than in 3D materials, permitting the fabrication of novel types of electronic devices (useful for computers that are faster and require less power). Additionally, the magnetic properties of electrons in 2D are unlike anything that occurs in 3D, which also has potential for new types of computing devices. The LT-STM will have impact not only for the researchers at Carnegie Mellon University, but also more broadly for the "Pittsburgh Quantum Institute", which includes about 50 faculty from University of Pittsburgh, CMU, and Dusquesne University. The proposed LT-STM will serve as a powerful characterization tool for research projects undertaken by members of this Institute. Technical AbstractFive investigators from Carnegie Mellon University (CMU) propose to acquire a low-temperature scanning tunneling microscope (LT-STM), including magnetic field capability. Two-dimensional (2D) materials and heterostructures will be studied. The 2D materials, which are only one or a few atomic layers thick, are formed by "exfoliation" from bulk crystals, that is, peeling off one or a few atomic layers from a bulk crystal and depositing those layer(s) on a suitable inert substrate. Such 2D layers exhibit a host of exotic properties including massless fermions, topologically protected states, superconductivity, and ferromagnetic phases, all of which will be probed in the LT-STM. Additionally vertical heterostructures will be formed by transferring one atomic layer atop the other; a state-of-the-art facility for performing such fabrication exists at CMU. Properties of the materials can be controlled in such heterostructures, since the presence of one layer in proximity to another yields collective behavior that differs from that of the individual layers. All of the investigators are active in directing graduate and undergraduate research, and the proposed LT-STM instrument will significantly enhance those activities. Additionally, the facility will impact theoretical studies presently performed at CMU related to the experimental work of the investigators. The instrument is also expected to have significant impact on the "Center for 2D Materials and Devices for Energy-Efficient Computing" at CMU, which four of the PIs are members of. An operating plan for the LT-STM has been formulated that will permit external users to have access to it. Four of the investigators are members of the "Pittsburgh Quantum Institute", which includes about 50 faculty from University of Pittsburgh, CMU, and Dusquesne University. The proposed LT-STM will serve as a powerful characterization tool for research projects undertaken by members of this Institute.