ARRA: Electron-Phonon interaction and Disorder: nanoscale Interference in Transport Phenomena

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). TECHNICAL SUMMARY This award supports theoretical research and education focused on electron-phonon kinetics and electric, thermal, and thermomagnetic transport in low-dimensional conductors, nanomaterials, and strongly correlated materials such as doped Mott dielectrics, e.g. novel superconductors and conducting polymers. Vibrating boundaries, defects, or dopants generates another channel of electron-phonon interaction, which interferes with the usual electron-phonon and elastic electron scattering. The interference of scattering mechanisms drastically modifies kinetic and transport phenomena. The interference effects can be strong and easily observable. While effects of interference have been known for some time, the research in this field is limited. The PIs will investigate electron-phonon kinetics and electric, thermal, and themomagnetic transport in low-dimensional structures, such as heterostructures, ultrathin films, multi-walled carbon nanotubes, nanowires, metallic clusters, and quantum dot arrays. In low dimensions, strong enhancement of interference effects is expected due to a smaller electron momentum transfer and due to intrinsic peculiarities in the momentum transfer related to the collective excitations. The PIs will investigate electron-phonon interference effects in specific materials, such as graphene and various doped Mott dielectrics. The research is aimed to contribute to the development of critical insights into the quantum interference of scattering mechanisms in kinetics and transport and will contribute to significantly improved theoretical techniques, related to the quantum transport equation and Feynman-Keldysh diagrammatic techniques. This research program contributes to developing effective ways to manage electron-phonon transport and energy transfer which will, in turn, strongly impact the development of advanced nanodevices and materials. A number of puzzling experimental results will find their explanation in the framework developed by this program. The project will have broader impacts through its contributions to education, and by developing theoretical models that can have impact in materials science and engineering. Nanoscale thermal management will substantially affect practically all branches of the electronics industry. This research will have immediate impact on the development of nanodevices in which energy transfer is ?tailored? to specific applications, e.g. ultrasensitive nanocalorimeters and single quanta nanodetectors operating at low and moderate temperatures. With graduate and undergraduate students, the PIs will develop a set of specialized experiments for elementary and high school students. These demonstrations are directly related to modern electronics and nanotechnology. The PIs will incorporate information technologies via Java Applets; they are extending these applets to incorporate the nanoworld energy transfer. They are also developing an interactive exhibit for the Physical World Science Studio of the Buffalo Museum of Science that will help to promote nanotechnology to a broader public. Lectures and demonstrations will be developed at a level appropriate for the general public. NON-TECHNICAL SUMMARY This award supports theoretical research aimed to elucidate the microscopic mechanisms that control how heat and electricity flow through materials structures and devices that are thousands of times smaller than the diameter of a human hair. The PIs will develop a theory on the level of electrons and the atomic-scale surfaces and defects, and vibrations that they encounter as they flow through these tiny structures. This project will contribute to the intellectual foundations for managing heat dissipation at small length scales anticipated for future circuit feature sizes of semiconductor devices. The heat generated by high speed electronic devices looms as one of the barriers to the continuing trend toward ever smaller electronic devices known as Moore?s law. This research will also contribute to the intellectual foundations of detector technologies on small length scales. With graduate and undergraduate students, the PIs will develop a set of specialized experiments for elementary and high school students. These demonstrations are directly related to modern electronics and nanotechnology. The PIs will incorporate information technologies via Java Applets; they are extending these applets to incorporate the nanoworld energy transfer. They are also developing an interactive exhibit for the Physical World Science Studio of the Buffalo Museum of Science that will help to promote nanotechnology to a broader public. Lectures and demonstrations will be developed at a level appropriate for the general public.