Atomic Resolution Dual-Point Superconducting Phase STM

原子分辨率双点超导相STM

• 批准号: 1409925
• 负责人: Frederick Wellstood
• 金额: $ 15万
• 依托单位: University of Maryland, College Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-01 至 2016-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1409925&HistoricalAwards=false
• 关键词: Atomic; Resolution; Dual; Point; Superconducting

Non-Technical:This award from the Condensed Matter Physics Program of the Division of Materials Research supports the development and proof of feasibility of a novel phase-sensitive superconducting dual-tip scanning tunneling microscope (STM) to generate novel atomic-resolution images. Since their invention in 1981, scanning-tunneling microscopes (STMs) have revolutionized the understanding of the physics of materials by providing images and detailed electronic information of solids down to the atomic scale. An STM creates an image by measuring the current from electrons that tunnel between a sample surface and an extremely sharp tip that is scanned very closely above the sample surface. Tunneling is a quantum-mechanical process that allows electrons to flow through regions that they are forbidden from entering by the laws of classical physics. The novel type of STM being developped uses two superconducting tips connected by a superconducting wire; it operates a fraction of a degree above absolute zero temperature, and allows the imaging of coherent Cooper pair tunneling. This project, when completed, will be used to study superconductivity at the atomic scale in conventional superconductors as well as newer materials which display exotic forms of superconductivity. Measurements made with a dual-tip superconducting STM can be used to probe the underlying mechanisms causing superconductivity. The project involves undergraduate and graduate students as well as postdocs.Technical AbstractThis award from the Condensed Matter Physics Program of the Division of Materials Research supports the development of a novel phase-sensitive superconducting dual-tip scanning tunneling microscope (STM) and the use of the instrument to generate novel atomic-resolution images and gain new insight into the mechanism producing superconductivity in high-transition temperature (Tc) superconductors and interesting phenomena in other materials. The system is based on a modification of an existing millikelvin STM in which two tips can be independently scanned, and can be either normal or superconducting, allowing for quasi-particle tunneling, or Cooper-pair tunneling in the quantum phase-fluctuation limit. By adding a superconducting wire connection between two superconducting tips, and using a superconducting sample, a Superconducting Quantum Interference Device (SQUID) loop is formed with the sample. With suitable biasing of the tips, this reduces fluctuations in the gauge-invariant phase difference across the nano-scale tips, allowing flux and phase sensitive imaging. In particular, this new capability will allow imaging of the spatial dependence of the gauge-invariant phase difference on the surface of superconducting samples at the atomic scale. The microscope will be tested at 35mK on well-understood superconducting materials such as Nb and Al and images generated of spatial variations in the local gauge-invariant phase difference near vortex cores, atomic defects, steps, and other surface irregularities. The project involves undergraduate and graduate students as well as postdocs.

非技术：该奖项来自材料研究部凝聚态物理计划，支持开发和证明一种新型相敏超导双尖端扫描隧道显微镜（STM）的可行性，以生成新型原子分辨率图像。自1981年发明以来，扫描隧道显微镜（STM）通过提供原子尺度的固体图像和详细的电子信息，彻底改变了对材料物理学的理解。STM通过测量在样品表面和非常接近样品表面上方扫描的非常尖锐的尖端之间隧穿的电子的电流来创建图像。隧道效应是一种量子力学过程，它允许电子流过经典物理定律禁止它们进入的区域。 正在开发的新型STM使用两个由超导导线连接的超导尖端;它在绝对零度以上的几度工作，并允许相干库珀对隧穿成像。该项目完成后，将用于研究传统超导体中原子尺度的超导性以及显示奇异形式超导性的新材料。 用双尖端超导STM进行的测量可以用来探测导致超导性的潜在机制。该项目涉及本科生和研究生以及博士后。技术摘要该奖项来自材料研究部凝聚态物理计划，支持开发一种新型相敏超导双尖端扫描隧道显微镜（STM），并使用该仪器生成新的原子分辨率图像，并获得对高转变温度（Tc）下产生超导性的机制的新见解。超导体和其他材料中有趣的现象。该系统是基于现有的毫开尔文STM的修改，其中两个提示可以独立扫描，可以是正常的或超导的，允许准粒子隧穿，或库珀对隧穿在量子相位波动限制。通过在两个超导尖端之间添加超导线连接，并使用超导样品，超导量子干涉器件（SQUID）回路与样品形成。通过尖端的适当偏置，这减少了跨纳米级尖端的规范不变相位差的波动，从而允许通量和相位敏感成像。特别是，这种新的能力将允许在原子尺度上超导样品表面上的规范不变相位差的空间依赖性的成像。该显微镜将在35 mK下对众所周知的超导材料（如Nb和Al）进行测试，并在涡核附近的局部规范不变相位差、原子缺陷、台阶和其他表面不规则性中产生空间变化的图像。该项目涉及本科生和研究生以及博士后。