Electrodynamics of Electron Liquids and Electron Glasses

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This individual investigator award will support an experimental project focusing on the low energy electrodynamics of novel materials with strong electron-electron interactions, disorder and reduced dimensionality. The materials to be investigated include: a) metals such as NbSi where the interplay of interactions and disorder leads to a metal-insulator transition and to a nonmetallic state, where quantum effects and randomness is essential; b) molecular nanowires, strictly one-dimensional chains of atoms such as Mo6Se6 where electron-electron interactions and/or disorder lead to a Luttinger Liquid in case of interactions, and an Anderson-Mott localized state in case of disorder; and c) metals such as UPt3 where electron-electron interactions are strong, the so-called heavy fermion systems. In the latter materials, magnetic correlations may place the materials close to a magnetic instability, which could be viewed as a Quantum Critical Point. In all cases the primary interest will be the so called quantum limit where the energy associated with the electromagnetic field is larger that the thermal energy, a region of the parameter space which has not been explored by experiments to date. The graduate students and post docs working on this project will receive excellent training that will prepare them for future careers in academia, industry, or government laboratories.%%%Electrons in materials can, just like atoms, assume an electron liquid, electron solid and electron glass state. In contrast to atomic arrangements, such states are more difficult to achieve and at the same time quantum effects play a more prominent role in most of the properties of such collective electron states. Because of the electronic charge, such states strongly interact with electromagnetic radiation, thus optical studies lead to fundamental information about such states. At the same time, development of such states lead to materials with unique, novel optical and electromagnetic characteristics. Typically the response to such radiation occurs at frequencies below the optical spectral range, at microwave, millimeter and sub-millimeter wave frequencies. This individual investigator award provides support to an experimental program that will explore the various electron states of matter, by developing new instrumentation and also by conducting novel type of experiments in the frequency ranges mentioned above on materials where such electron states occur. The graduate students and post docs working on this project will receive excellent training that will prepare them for future careers in academia, industry, or government laboratories.