A Crossover of Molecular and Extended Magnetism in Engineered Solids

Iowa State University, Ames IA

Investigators

Abstract

Part I: Non-technical Summary Magnetic materials have shaped our modern society because they are crucial for advances in the fields of renewable energy, electric engines, sensors, and data storage. There are two types of magnetic materials - molecular magnets, composed of isolated molecules, and extended solid or itinerant magnets with infinite frameworks of chemical bonds within the crystal structure. Molecular magnets are appealing due to their synthesis at low temperatures and high tunability but suffer from weak magnetic interactions. In turn, extended solid magnets exhibit strong magnetic interactions and large magnetic moments in the ordered state but have limited tunability. The current project is focused on bridging the gap between molecular and extended solid magnets by synthesizing a unique set of hybrid compounds, which combine advantages of both classes of magnetic materials. In the proposed hybrid compounds, tunable molecular fragments will be sandwiched in between one- and two-dimensional fragments of extended solid magnets. Understanding how structure determines properties is the key step for design of emerging materials. Thus, to achieve significant breakthroughs in the magnetic materials development, we are establishing fundamental relationships between structure and nature of interactions of molecular and extended fragments, and magnetic properties of the produced materials. In the educational component of the project, chemistry graduate and undergraduate students are engaged in chemistry demonstrations at local elementary schools, the Iowa State STEM Program for Women in Science and Engineering, and the Des Moines Science Center to foster interest of K-12 students and adults in chemistry. This project is supported by the Solid State and Materials Chemistry Program in the Division of Materials Research. Part II: Technical Summary Exploration of chemical factors that affect magnetic interactions in solids is one of the major steps in the development of novel magnetic materials. Current solid state syntheses lack the predictability and rationality of organometallic and coordination chemistry. To achieve high predictability and rationally design magnetic materials, hybrid magnetic materials comprising infinite Fe-chalcogenide fragments separated by interstitial coordination metal complexes are being developed. In this way, strong magnetic interactions and tunability are segregated into two different sublattices of a hybrid material. The project uses coordination chemistry methodology to tune molecular transition metal amine complexes which are incorporated in between or connected to extended infinite Fe-chalcogenide fragments of itinerant magnets. It is anticipated that chirality and spin-crossover properties of coordination complexes will be translated to the itinerant Fe-chalcogenide fragments. An advantage of the target hybrids is that strong magnetic interactions and large magnetic moments present in the Fe-chalcogenide sublattice will either amplify the weak magnetic signatures of spin-crossover transitions or produce chiral magnets. In the educational component of the project, chemistry graduate and undergraduate students are engaged in chemistry demonstrations at local elementary schools, the Iowa State STEM Program for Women in Science and Engineering, and the Des Moines Science Center to foster interest of K-12 students and adults in chemistry. This project is supported by the Solid State and Materials Chemistry Program in the Division of Materials Research. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.