Electronic Transport in Microwave-Driven GaAs/AlGaAs Quantum Structures

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This experimental condensed matter physics project will investigate the newly discovered phenomena of (i) radiation-induced resistance oscillations, and (ii) zero-resistance/zero-conductance states, in a two-dimensional electron gas exposed to millimeter wavelength radiation. The experiments will focus on three major thrusts: (1) Novel effects in dc electronic transport induced by microwave excitation in a small magnetic field; (2) Nonlinear optical effects in the millimeter wave regime and their influence on dc electronic transport; and (3) The prospect for imaging the electrical currents and flux states in a microwave-pumped quantum structure. The proposed work will continue to explore interesting physics, in particular the current pattern formations in the semi-classical and quantum regimes, and possible flux states in a microwave-pumped electronic system. Education of graduate students familiar with semiconductor physics, microwave technology, and imaging technique serves them well for employment in the national research infrastructure and high-technology industry. Electrical transport in a semiconductor device can exhibit vanishing resistance when it is exposed to microwave radiation, a new effect which was discovered by the PI during the previous grant period. This proposal seeks funding to continue this investigation, with experiments focused on three major aspects: (1) Novel effects in electronic transport induced by microwave excitation in a small magnetic field; (2) Nonlinear optical effects in the millimeter wave regime and their influence on electronic transport; and (3) The prospect for imaging the electrical current distribution in a microwave-pumped quantum device. Understanding of fundamental properties of a semiconductor device driven by microwaves is also directly relevant to emerging issues in spintronics and quantum information science. Education of graduate students familiar with semiconductor physics, microwave technology, and imaging technique serves them well for employment in the national research infrastructure and high-technology industry.