Experimental Studies of Quantum Dynamics of Electrons in Disordered Metals

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9423088 Carini This project investigates the microwave conductivity (up to a frequency of 20 megahertz) of disordered metals in which the electrons are close to a localization transition, such as ultrathin metal films and highly disordered metal alloys. Experiments will compare the dc and microwave conductivity as a function of temperature (T30mK) and magnetic field (B8T). Theses measurements will test the predictions of the scaling theory, which treats the transition as a quantum-critical point where the temperature, alloy concentration, and frequency dependence of the conductivity are related to the same critical length-scale. % % % The proposed experiments study the transition from the metallic state to the insulating state that occurs in disordered materials when the electrons become localized in space. The localization transition occurs because of the wavelike behavior of the electrons as quantum mechanical particles, and yet the transition is a collective phenomenon where all parts of the system undergo the same change of state at the same time. The experiments will measure the electrical conductivity in disordered metals in order to understand how quantum mechanics affects the transition between the conducting and insulating states. ***