Non-Technical Abstract: The objective of this research is to explore and understand the microscopic origins of various phases in iron-based superconductors, specifically the iron arsenide superconductors BaFe2-xNixAs2, (B,K)Fe2A2, and BaFe2As2-xPx, using neutron scattering as a primary tool. The research has two components: initial materials characterization and neutron scattering. For synthesis, a comprehensive materials laboratory was established and single crystals of the proposed materials can be grown at Rice. The initial characterization of these single crystals is performed using facilities at Rice. Neutron scattering, the core part of this research program, is used to study the spin dynamical properties of these materials. In particular, the effect of uniaxial pressure on their structural, magnetic, and spin dynamical properties are studied. Uniaxial pressure can also detwin the sample and allow twin-free states of these materials to be explored.
This NSF project addresses the fundamental physical processes that give rise to novel collective phenomena such as high-transition temperature superconductivity. The materials known to exhibit these collective phenomena are the strongly correlated electron materials. The understanding of these phenomena not only enhances our knowledge of basic science, but also give us the ability to design materials with novel and predictable properties. Specifically, the experimental research includes neutron scattering experiments aimed at the fundamental understanding of the spin excitations in a family of iron-based high-transition-temperature superconductors. The objective of the research is to explore and understand the microscopic origins of various phases of iron-based superconductors using neutron as a probe. Neutron scattering experiments are performed mostly at the high-flux isotope reactor (HFIR) and Spallation Neutron Source (SNS) at the Oak Ridge National Laboratory. However, the project also utilizes other world-class facilities in the U.S. and Europe when similar capabilities are unavailable at HFIR and SNS. The impact of this research includes the training of the next generation of neutron scatters and elucidating the nature of the exotic properties of the correlated electron materials.
