Two-Dimensional Nanosheets of Magnetic Lanthanide Chalcogenides

With the support of the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry, Professor Sarah Stoll of Georgetown University will develop synthetic routes to novel two-dimensional materials with useful magnetic properties. This project focuses on materials with structures that are naturally layered, with strong covalent bonds within the layer and weak interactions between layers, similar to graphite. A deeper fundamental understanding of how structure and nanosheet thickness determine magnetic coupling and orientation will be key for designing new devices that take advantage of both electronic and magnetic properties, i.e. spintronics. This project will provide research training to graduate and undergraduate students. An interactive workshop that focuses on environmental chemistry and ethics issues will be developed and adapted for a local girls high school. The investigation will focus on three classes of lanthanide (Ln) materials that vary systematically in structural anisotropy, inter-layer bonding, magnetic orientation and electronic conductivity. The first family are the tritellurides, LnTe3, which are van der Waals layered XY magnets in which moment is in the plane of the sheets. Slightly less anisotropic are the ditellurides, LnTe2, ionic-layered Ising magnets in which moment is perpendicular to the plane of the sheets. Finally, the third family are the isotropic monochalcogenides such as EuTe; these are Heisenberg, three-dimensional magnetic semiconductors. The synthetic methods developed will be important for expanding the synthetic range of two-dimensional materials. These materials exhibit a wide range of properties whose further study can extend their utility for next-generation devices. 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.