Low Temperature Scanning Probe Microscopy

University Of Texas At Austin, Austin TX

Investigators

Abstract

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.