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

非技术性摘要卡内基梅隆大学的五位教授将通过NSF MRI计划获得一台低温扫描隧道显微镜(LT-STM)。这种仪器可以在低温和强磁场下绘制表面上的原子排列图。研究的重点将是“二维(2D)材料”，即只有一层原子厚度的材料。在这种材料中，电子被限制在单个原子层内运动，因此它们获得了常规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层将堆叠在另一个层的顶部。这种2D材料的组合具有同样不同于常规三维材料的任何属性。例如，人们发现电子在2D材料中的运动速度比在3D材料中快得多，这使得制造新型电子设备成为可能(对于速度更快、需要更少电力的计算机来说很有用)。此外，2D中电子的磁性与3D中的任何东西都不同，3D中的电子也有可能开发出新型计算设备。LT-STM将不仅对卡内基梅隆大学的研究人员产生影响，还将更广泛地影响“匹兹堡量子研究所”，该研究所包括来自匹兹堡大学、CMU和杜斯昆大学的约50名教职员工。拟议的LT-STM将成为本研究所成员开展的研究项目的一个强有力的定性工具。技术摘要来自卡内基梅隆大学(CMU)的五名研究人员提议获得一种包括磁场能力在内的低温扫描隧道显微镜(LT-STM)。将研究二维(2D)材料和异质结构。这种只有一个或几个原子层厚的2D材料是由大块晶体剥离形成的，即从大块晶体上剥离一个或几个原子层，并将这些层(S)沉积在合适的惰性衬底上。这样的2D层表现出许多奇异的性质，包括无质量的费米子、拓扑保护态、超导电性和铁磁性相，所有这些都将在LT-STM中被探测到。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来形成；CMU有一台最先进的设备来进行这种制造。材料的性质可以在这种异质结构中控制，因为一层靠近另一层的存在会产生与单独层不同的集体行为。所有研究人员都积极指导研究生和本科生的研究，拟议的LT-STM仪器将显著加强这些活动。此外，该设施将影响目前在CMU进行的与调查人员的实验工作有关的理论研究。预计该仪器还将对CMU的“2D材料和设备节能计算中心”产生重大影响，其中四名PI是该中心的成员。已经制定了LT-STM的运行计划，允许外部用户使用它。其中四名调查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、芝加哥大学和杜斯昆大学的约50名教职员工。拟议的LT-STM将成为本研究所成员开展的研究项目的一个强有力的定性工具。

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.