Investigation of Strongly Correlated Itinerant Magnets and Potential Quantum Spin Liquids

Florida State University, Tallahassee FL

Investigators

Abstract

NON-TECHNICAL SUMMARY Advanced magnetic materials are crucial to a number of current and upcoming technologies that are critical to our nation's energy security. Among these are electric vehicles, wind turbines, magnetic refrigerators, and high-density data storage devices. The improvement of such technologies relies on our ability to discover new and optimize existing magnetic materials by developing fundamental understanding of correlations between crystal structure and magnetic behavior. With support from the Solid State and Materials Chemistry program in the Division of Materials Research, this research project targets the exploration of materials whose magnetic properties are highly sensitive to subtle changes in the crystal and electronic structures. Such solids will demonstrate abrupt changes in the magnetic behavior upon minor external perturbations (e.g., temperature or pressure) and can offer pathways to devices that operate at lower powers and exhibit higher energy-conversion efficiencies. The project will provide training for graduate and undergraduate students in solid state chemistry, materials synthesis, crystallography, magnetism, and energy-conversion technologies. The research team will also develop a comprehensive open-access online database for strongly correlated magnetic materials. The PI has a proven track-record of involving underrepresented groups and undergraduate students in research endeavors, and will continue to maintain this practice in his research and outreach activities. TECHNICAL SUMMARY Itinerant magnetism provides the foundation for high-performance permanent and soft magnetic materials. This research project focuses on the investigation of two classes of magnetic materials, both of which leverage strong correlations in the electronic band structure that translates into unconventional magnetic behaviors. Ternary arsenide and boride intermetallics will be investigated vis-a-vis the sensitivity of their magnetic properties to peculiarities of crystal and electronic structures. The latter will be perturbed via judicious changes in chemical composition or application of external pressure. Both chemical and physical perturbations can induce valence fluctuations that will translate into strong changes in magnetism demonstrated by these materials. A close attention will be paid to the nature of 3d-4f magnetic exchange to formulate general expectations for the type of interlattice magnetic coupling in each group of materials. The research team will also investigate ternary selenides with low-dimensional structures that result in strong magnetic frustration. Such materials are predicted to avoid long-range magnetic ordering, thus leading to exotic quantum states, e.g., spin liquids or Haldane-gap systems. The proposed research activities will provide versatile training to graduate and undergraduate students in materials synthesis, investigation of structural and magnetic properties, and studies of the electronic band structure.