Imaging the Gauge-Invariant Phase Difference of Superconductors

超导体规范不变相位差的成像

• 批准号: 0605763
• 负责人: Frederick Wellstood
• 金额: $ 39万
• 依托单位: University of Maryland, College Park
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-08-01 至 2011-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0605763&HistoricalAwards=false
• 关键词: Imaging; Gauge; Invariant; Phase; Difference

Non-Technical:This project will construct a novel type of scanning tunneling microscope and use it to study superconductors at the atomic scale at temperatures that are a small fraction of a degree above absolute zero. The microscope includes a sharply pointed tip, which can be moved in a controlled manner across a surface under study, and the associated electronics for measuring the electric current that flows between the tip and the surface. Changes in this current (the tunneling current) as the tip is moved over the surface indicate variations in the properties of this surface. The goal of the project is not only to develop a new type of imaging but also to obtain insight into the as yet unknown mechanism that is producing high-temperature superconductivity. Knowledge of this mechanism could lead to new superconductors with transition temperatures that are high enough to have a significant impact on technology. Other broad impacts include training of graduate students and postdoctoral students in areas of continuing scientific and technological importance, including low-temperature physics, microscopy at the atomic scale, materials physics, and superconductivity. The project will work to increase the participation of women and minorities in the physical sciences, improve undergraduate and graduate education in physics, and foster collaborations with scientists from Latin America and Eastern Europe.Technical:This project will build a novel type of low temperature scanning tunneling microscope (STM) and use it to measure spatial variations in the phase difference of superconductors at the atomic scale. This microscope consists of a Josephson junction connected in parallel with a vacuum tunnel junction, which is formed between the superconducting STM tip and the surface of the superconductor under study. To minimize the impact of thermally generated noise, the entire system will be cooled in a dilution refrigerator to below 0.1 K. After testing on a well-understood superconducting material, the system will be used to examine spatial variations in the local phase difference near atomic defects, steps, grain boundaries and other surface irregularities and ultimately to probe the unknown mechanism causing superconductivity in the high-transition temperature (Tc) superconductors. The project will support the training of graduate students and postdoctoral students in areas of continuing scientific and technological significance, including low-temperature physics, scanning near-field microscopy, materials physics and superconducting devices. The project will work to increase the participation of women and minorities in the physical sciences, improve undergraduate and graduate education in physics, and foster collaborations with scientists from Latin America and Eastern Europe.

非技术性：该项目将建造一种新型扫描隧道显微镜，并用它在比绝对零高一点点的温度下研究原子尺度的超导体。该显微镜包括一个尖锐的尖端，可以以受控的方式在所研究的表面上移动，以及用于测量尖端和表面之间流动的电流的相关电子设备。当尖端在表面上移动时，该电流（隧道电流）的变化表明该表面特性的变化。该项目的目标不仅是开发一种新型成像技术，而且是深入了解产生高温超导性的未知机制。了解这种机制可能会导致新型超导体的转变温度足够高，对技术产生重大影响。其他广泛的影响包括对研究生和博士后学生进行持续科学和技术重要性领域的培训，包括低温物理学、原子尺度显微镜、材料物理学和超导性。该项目将致力于增加女性和少数族裔对物理科学的参与，改善物理学本科和研究生教育，并促进与拉丁美洲和东欧科学家的合作。技术：该项目将建造一种新型低温扫描隧道显微镜（STM），并用它来测量原子尺度超导体相位差的空间变化。该显微镜由与真空隧道结并联连接的约瑟夫森结组成，真空隧道结形成在超导 STM 尖端和所研究的超导体表面之间。为了最大限度地减少热噪声的影响，整个系统将在稀释冰箱中冷却至 0.1 K 以下。在对一种众所周知的超导材料进行测试后，该系统将用于检查原子缺陷、台阶、晶界和其他表面不规则性附近局部相位差的空间变化，并最终探索在高转变温度下导致超导性的未知机制 (Tc) 超导体。该项目将支持在具有持续科学技术意义的领域培养研究生和博士后，包括低温物理、扫描近场显微镜、材料物理和超导器件。该项目将致力于增加女性和少数族裔对物理科学的参与，改善物理学本科和研究生教育，并促进与拉丁美洲和东欧科学家的合作。