Magnetic Correlations Through Metal-Insulator Transition in Strongly Correlated Electron Materials

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***NON-TECHNICAL ABSTRACT***Understanding how complex behavior emerges from simple and basic laws is one of the areas of current interest in Condensed Matter Physics. This individual investigator project addresses the fundamental physical processes that give rise to novel phenomena, such as high-transition temperature superconductivity and colossal magnetoresistance (where a material displays a very large change in its electrical resistance when exposed to a magnetic field), resulting from the collective behavior of electrons. Materials in the family known as transition metal oxides (TMOs) exhibit these collective phenomena. Understanding these phenomena will not only enhance our knowledge of basic science, but also gives us the ability to design materials with novel and predictable properties. The objective of the program is to explore and understand the microscopic origins of various phases in the TMOs using neutrons as a probe. Neutron scattering experiments will be performed mostly at the upgraded high-flux isotope reactor (HFIR) at the Oak Ridge National Laboratory (ORNL) and on the new spallation neutron source at ORNL. The project will also utilize other world-class facilities in the U.S. and Europe when similar capabilities are unavailable at ORNL. The impact of this research program will include the training of the next generation of neutron scatters and elucidating the nature of the exotic properties of the TMOs. ***TECHNICAL ABSTRACT***This individual investigator project will establish an experimental program integrating neutron scattering experiments with lab based materials efforts. The aim of the project is to further our understanding of the phase transition from a Mott insulator to a metallic/superconducting state in transition metal oxides (TMOs). The objective of this research program is to explore and understand the microscopic origins of various phases in the TMOs using neutron scattering as a primary tool. The project will focus on electron-doped high-Tc superconductors and colossal magneto-resistance (CMR) manganese-oxides. The program has two components: advanced synthesis with initial materials characterization and neutron scattering. Neutron scattering, the core part of this research program, will be used to study the exotic spin and lattice dynamical properties of the highly correlated electron materials. Most experiments will be performed at the newly upgraded high-flux isotope reactor (HFIR) at the Oak Ridge National Laboratory (ORNL). However, other world-class facilities in the U.S. and Europe will be utilized when similar capabilities are unavailable at HFIR. Students will be trained in state-of-the art materials synthesis and neutron scattering techniques.