Low - Dimensional Transition Metal Oxides with Correlated Electronic Properties: Synthesis and Characterization

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TECHNICAL SUMMARYThe focus of the experimental program, supported by the Solid State and Materials Chemistry program is to synthesize new materials with strongly correlated electronic properties that are on the verge of electronic and structural instabilities, and to fine-tune the competing electronic interactions through the unstable region in a controlled way. Experience shows that materials with novel behavior are likely to be discovered when competing electronic interactions exist. In low-dimensional (LD) materials the interplay of competing electronic interactions is enhanced. The object of this project is the synthesis and characterization of new reduced/oxidized-transition metal compounds with quasi-LD properties. A number of systems will be investigated which share the common feature of interplay between localized and itinerant degrees of freedom, a highly variable conduction electron bandwidth, which may be tuned by changing e.g., the crystal structure, chemical composition, external strain and degree of disorder. The variability of bandwidth leads to a variety of important phenomena, including metal-insulator transitions (or sharp crossovers) driven by variation of temperature, pressure, magnetic field, electric field, illumination, lattice distortion and other variables. We expect that in the vicinity of these transitions the transport, electronic/magnetic properties will also change dramatically and will be tunable. The experimental studies will be augmented by theoretical investigation of the electronic structure by density functional theoretical calculations. These studies are expected to yield novel materials, provide fundamental insights into correlated electronic and magnetic behavior and ultimately allow the enhancement and control of electron-phonon and/or electron-electron interactions and the concurrent magnetic couplings that lead to interesting and useful macroscopic properties. NON-TECHNICAL SUMMARYThe research will provide advanced materials for potential applications in microelectronics and magneto-electronics, including computers, sensors and communications. These are critical areas for maintaining US technological leadership worldwide. Moreover, the education and training of undergraduate and graduate students and postdoctoral fellows in solid state chemistry/materials science is essential to meet the technological challenges of the twenty first century. The research proposed is highly interdisciplinary. Collaborative work of the PI with other chemists, physicists and ceramicists is well established nationally and internationally. Single crystals and other material products of the work are provided to the scientific community for detailed further investigations.