Thin Films, Heterostructures and Mesoscale Physics of Quasi-One-Dimensional Conductors

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w:\awards\awards96\num.doc Thorne 9705433 This experimental project focuses on the properties of interfaces involving thin films of novel charge-density wave (CDW) conductors, including Rb0.3MoO3. Materials of this class are among the most remarkable conducting materials ever discovered, and have many novel and potentially useful properties. In part the work will build upon the recent demonstration by van der Zant et al at the Delft University of Technology, that thin films of CDW conductors can be prepared, patterned and characterized, which indeed demonstrate the novel and potentially useful CDW phenomena. Collaboration with this group and the Buhrman group at Cornell will explore pulsed laser depostion of these materials. Methods for patterning and for attaching contacts to indvidual grains, and for preparing heterostructures with other materials will be investigated. These films make possible a broad variety of experiments to probe mesoscale aspects of CDW physics, and several such experiments are planned. In addition, memory devices based on metastable CDW states will be fabricated and characterized. Mesoscopic structures will be used to study CDW phase slip and vortex dynamics. MOSFET-like heterostructures will allow modulation of the CDW wavevector, gap and collective conductance. Such devices may be useful as detectors and mixers. CDW-superconductor heterostructures will be used to explore proximity effects due to the competing pairing interactions in these two ground states. Preliminary efforts to test predictions for the properties of mesoscale CDW-insulator-CDW and normal metal-insulator-CDW heterostructures will also be undertaken. This research project is interdisciplinary in nature and will involve graduate and undergraduate students who will be excellently trained for careers in industry, government and a cademia. %%% This experimental project is based on novel and potentially useful electronic conducting films of "charge-density-wave" conductors. In these materials, which are typically very anisotropic, often needle-like in their shape, electrical conduction occurs in a completely different way than in common metals such as copper and aluminum. In these conductors a cooperative motion of charge-carrying "domains" provides conduction, with many novel and potentially useful properties. In this project, thin films of such materials, suitable for incorporation into electronic device configurations, such as "mixers" of use in high frequency communication equipment, will be fabricated and studied. Heterojunctions of such films will resemble in some cases the "MOSFET" structures well known in the silicon device technology, and will be explored for their novel properties. This work will lead to a much better understanding of the electrical behavior of interfaces between conventional metals and insulators and the novel charge-density-wave conductors, and will possibly lead to new applications in electronics. This research project is interdisciplinary in nature and will involve undergraduate and graduate students who will be excellently trained for positions in industry, government and academia. ***