NSF-Europe: Correlated Phenomena in Atomically Arranged Transition Metal Perovskites

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Collaborative materials research will be undertaken on strongly correlated bulk and single-crystal transition metal perovskite-related compounds with atomically arranged local structure. New compounds with tailored characteristics will be designed and an in-depth investigation of their properties and property correlations will be performed to demonstrate the new materials' potential applications. During this process, it is expected that novel collective phenomena and ground states, quite different from conventional superconductors, magnets, and dielectrics will be discovered in the tailored materials. The research will focus on developing new synthesis tools, measurement techniques of structural, physical, and chemical properties over a wide range of length scales, and the description of these properties in terms of geometrical constraints, interatomic distances, and ionic coordinations. By expanding existing European collaborations, and developing new ones, the project will build on the Laboratory for Materials Design at Northern Illinois University's extensive experimental capabilities and expertise in crystal chemistry of complex oxide compounds. Novel layered RAMnMO6-? (R = La, Y, Rare Earth's; A = Ba, Sr, Ca; M = Transition Metals) materials will be explored for enhanced magnetic and magneto-dielectric properties. A focused effort will explore the concepts of tolerance factor and the variances of sizes and charges to reliably describe the thermodynamic stability and prediction of structural and physical properties of perovskites of Mn, Fe, and Ni and double-perovskites (atomically Na/Cl-type ordered) of RAMM'O6. These systematic strategies will be used for developing new manganese-oxide materials with closely matched lattice parameters and improved magneto-resistive, thermal and mechanical properties. Coordinated materials research in a broad range of novel, highly overdoped copper-oxide superconductors will focus on the effects of external fields and pressures on anisotropic magnetic and transport properties to discern the nature of the conducting behavior. The Mo and Sr substituted CuBa2YCu2O7-d single-crystals will be grown, critical superconducting parameters will be measured, and their properties will be correlated to engineered atomic order to conclusively demonstrate the compounds' potential for application as high current conductors and sources of high magnetic field. This international collaboration entails the systematic exploration of the effects of composition, temperature, and oxygen content on thermodynamic stability and physical properties of atomically ordered transition metal perovskites. It will produce new insights into many-body physics of transition metal oxides, electron correlations, and the occurrence of novel ground states; it will also provide new tools for tailoring the production of desired properties. The project's impact derives from the increased understanding it will promote of the organization and control of matter on the atomic scale that will lead to future application of perovskites in all-oxide multifunctional magnetic/dielectric/electronic devices. It is expected that improved magneto-resistive, dielectric, and superconducting materials will result from the enhanced understanding of the crystal chemistry of perovskites and advancement of synthesis and characterization tools. %%%This NSF project is co-funded by the Division of Materials Research and the International Office (Western Europe and Poland) as a Cooperative Activity in Materials Research between the NSF and Europe (NSF 02-135). This project is being carried out in collaboration with the Laboratoire Crismat-ISMRA, Caen, France, Dr. A. Maignan; University of Cambridge, United Kingdom, Prof. J. Paul Attfield; Institute of Physics, Polish Academy of Sciences, Warsaw, Poland, Dr. A. Wisniewski; and Institute of Low Temperature and Structural Research, Polish Academy of Sciences, Wroclaw, Poland, Dr. K. Rogacki.