Low Temperature Scanning Probe Microscopy

在这个项目中，将开发一种新的设计，以前从未考虑过的双尖端扫描隧道显微镜（STM）。在这种设计中，两个尖端从相反的侧面探测非常薄的样品。此外，将设计另一种双尖端STM，其中两个尖端以更传统的几何形状探测样品，两个尖端位于样品的同一侧。研究人员最近开发的纳米管尖端使这些设计成为可能。纳米管尖端可能是理想的自旋极化隧道，以及许多科学和实际应用，这些应用可以受益于自旋极化电子的相干点源。双尖端STM将使探测样品材料格林函数的新实验成为可能，因此人们可以获得半导体或金属样品的详细信息，如平均自由程，杂质散射的相和能量依赖，带结构的细节，以及从弹道到扩散输运的转变。该仪器还可以探测超导体中有序参数的对称性，从而可以对高温超导的电流d波图进行改进。研究生和本科生将参与这个项目。他们将受益于先进仪器和技术的培训，新型STM仪器的开发，以及使用它以最详细的方式探测电子的行为。随着显微镜探测小细节的能力不断增强，它已成为增进我们对材料微观结构和行为理解的主要工具。扫描隧道显微镜（STMs）是这种仪器的最新类型，现在可以在原子水平上探测材料。在这个项目中，将开发一种基于使用两个而不是一个探针尖端的新型STM。一个版本将在一个非常薄的样品的相对两侧有两个尖端，这是一种以前从未考虑过的几何形状。双尖端STM的第二个版本将采用更传统的几何形状，其中两个尖端位于样品的同一侧。这两种版本都可以在探针尖端的基础上实现，探针尖端是原子尖的针（碳纳米管），是最近在研究人员的实验室开发的。这种双尖端STMs将允许对材料特性进行一系列新的研究，包括高温超导化合物，这将有助于更好地了解它们的结构和行为。这些结果最终将对技术有用和有益。这个项目将涉及研究生和本科生的参与。他们将因此获得凝聚态物理和材料科学这一非常活跃的当代领域的知识和技能。这将使他们成为本世纪未来几十年科学/技术劳动力中富有成效的成员

In this project a two-tip scanning tunneling microscope (STM) of a new design, never considered before, will be developed. In this design the two tips probe a very thin sample from opposite sides. In addition, another two-tip STM will be designed in which the two tips probe the sample in a more conventional geometry, with both tips on the same side of the sample. Nanotube tips recently developed by the investigator enable these designs. Nanotube tips may be ideal for spin-polarized tunneling, as well as for a host of scientific and practical applications that can benefit from a coherent point source of spin-polarized electrons. The two-tip STM will make possible new experiments that will probe the Green function of the sample material, so that one can get detailed information on semiconducting or metallic samples such as mean free path, the phase and energy dependence of scattering from impurities, details of the band structure, and the transition from the ballistic to diffusive transport. This instrument can also probe the symmetry of the order parameter in a superconductor, so that refinements of the current d-wave picture can be obtained for high temperature superconductivity. Graduate and undergraduate students will participate in this project. They will benefit from training in advanced instrumentation and techniques, in the development of the novel STM instrument, and from using it to probe the behavior of electrons in the most detailed fashion yet available.%%%Microscopes with ever increasing ability to probe small details have been major instruments in advancing our understanding of the microscopic structures and behaviors of materials. Scanning tunneling microscopes (STMs) are the latest types of such instruments that now allow the probing of materials at the atomic level of dimensions. In this project, a new type of STM, based on the use of two, rather than one, probe tips will be developed. One version will have the two tips on opposite sides of a very thin sample, a geometry that has never before been even contemplated. A second version of the two-tip STM will be of a more conventional geometry, in which the two tips are on the same side of the sample. Both versions can be realized on the basis of probe tips, which are atomically sharp needles (carbon nanotubes), that were recently developed in the investigator's laboratory. Such two-tip STMs will allow a new set of investigations of the properties of materials, including high temperature superconducting compounds that will result in a better understanding of their structure and behavior. These results will ultimately be of use and benefit to technology. This project will involve the participation of graduate and undergraduate students. They will thereby acquire knowledge and skills in a very active contemporary area of condensed matter physics and materials science. These will enable them to be productive members of the scientific/technological workforce of the next few decades of this century.***