Coherent Phonon Dynamics in Semiconductors and Nanotubes

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TECHNICAL SUMMARY:This award supports integrated research, education and outreach activities in theoretical condensed matter physics. The goal of this research program is to develop new theoretical models and investigate ultrafast generation of coherent phonons in semiconductors. A key question being addressed is whether such phonon dynamics can be manipulated to influence magnetic and electric polarization to the extent that it has device potential.These research investigations are looking into three new areas to theoretically describe the interactions of the photogenerated coherent phonons with carriers and spins that are already present in the nanostructures under conditions of high electric and magnetic fields and in novel materials such as carbon nanotubes. Researchers will investigate the use femtosecond pulse shaping to manipulate the electric and magnetic fields as well as the carrier, phonon and spin dynamics. The coherent control of magnetic and electric fields and carrier or spin dynamics on an optical time scale will have a broad impact on future device design. Through control of these features with coherent phonons, a variety of novel and interesting possibilities for future device applications in emerging fields such as spintronics or quantum information theory will be garnered. Graduate students will participate in this research effort and benefit by learning theoretical techniques and understanding the materials and technology associated with nanoscience. This work will be the basis for dissertation research leading to the PhD. The principle investigator has record of acting as a mentor of young students and participating in outreach efforts of the department of physics, activities which will continue during this research project.NON-TECHNICAL SUMMARY:Integrated research, education and outreach activities in theoretical condensed matter physics combine as the core activities under this award. The primary motivation of the project stems from the phenomena of atomic vibrations, like sound, generated by lasers in semiconductor materials. The pure frequencies of ultra short laser pulses produce similarly pure and large "sound" waves. These are sufficiently large that the "sound" alters the electric and magnetic properties of the material A goal of this research program is to develop new theoretical models to understand this effect and control it. The characteristic that this occurs extremely fast and in a small area leads to the potential for optical control of the smallest possible electronic devices that are being developed in the field of nanotechnology. Graduate students will participate in this research effort and benefit by learning theoretical techniques and understanding the materials and technology associated with nanoscience. This work will be the basis for dissertation research leading to the PhD. The principle investigator has record of acting as a mentor of young students and participating in outreach efforts of the department of physics, activities which will continue during this research project.