Low Temperature Scanning Probe Microscopy

该项目强调使用扫描探针显微镜的独特功能来研究新材料，如高温超导体、锰矿化合物、稀磁性半导体，以及这些材料的组合或纳米结构版本。研究生和本科生在设计和开发复杂的仪器和凝聚态物理当前感兴趣的材料的性质训练。该项目的前沿推力是开发一种低温扫描隧道显微镜，其两个尖端可以位于彼此相距100纳米的范围内，其目标是探测各种材料的绿色功能。这将提供有关半导体或金属样品的详细信息，例如它们的平均自由程，杂质散射的相位和能量依赖，带结构的细节，以及从弹道到扩散输运的转变。这台仪器还将允许测试一个预测，即两个相邻纳米管中的电子将通过与超导表面接触而产生量子力学纠缠。自20世纪80年代初以来，扫描探针显微镜对科学技术产生了巨大的影响，因为它们能够研究和操纵原子水平的表面。这个项目延续了这一传统，设计和建造了这些仪器，并使用它们来研究新材料。最近的工作，使用这些扫描探针的方法，已经显示出新的磁性材料的新特性，具有巨大的潜力，作为传感器或存储介质。另一个例子是使用碳纳米管作为扫描探针显微镜的尖端。其中一些工作可能具有显微镜以外的技术应用，例如使用减少或消除静摩擦的新想法开发的微定位器。参与这些项目的研究生和本科生，其中一些是西班牙裔，因此在复杂仪器的设计和开发以及新材料的特性方面受到培训，其中一些有希望用于商业和/或国防应用。

This project emphasizes the use of unique capabilities in scanning probe microscopy for the study of novel materials, such as high temperature superconductors, manganite compounds, dilute magnetic semiconductors, and combined or nanostructured versions of these. Graduate and undergraduate students are trained in the design and development of sophisticated instruments and on the properties of materials of current interest in condensed matter physics. The forward thrust of the project is the development of a low temperature scanning tunneling microscope with two tips that can be located within 100 nm from each other, with the goal of probing the Green function of a wide gamut of materials. This will give detailed information about semiconducting or metallic samples such as their mean free path, the phase and energy dependence of scattering from impurities, details of the band structure, and the transition from ballistic to diffusive transport. This instrument will also allow the test of a prediction that electrons in two neighboring nanotubes will become quantum mechanically entangled via contact with a superconducting surface.%%%Scanning probe microscopes have had a tremendous impact on science and technology since the early 1980's because of their ability to study and manipulate surfaces down to the atomic level. This project continues this tradition in the design and construction of such instruments, and of their use to study new materials. Recent work, using these scanning probe methods, has shown novel properties of new magnetic materials that have great potential for use as sensors or memory media. Another example is the use of carbon nanotubes as tips for scanning probe microscopes. Some of this work may have technological applications beyond microscopy, such as the micropositioner developed using novel ideas that reduce or eliminate static friction. Graduate and undergraduate students participating in these projects, some of whom are Hispanic, are thus trained in the design and development of sophisticated instruments and on the properties of new materials, some of which are promising for commercial and/or defense applications.