Engineering the Properties of Orbitronic Nanomaterials

Major Goals: We will utilize the unique interplay of geometry, shape and confinement in nanomaterials along with symmetry breaking and precisely tailored fields to produce and probe nontrivial and unprecedented optoelectronic functionalities in topological materials. Our vision is that novel electronic and optoelectronic phenomena are accessible by controllably fabricating nano materials into desired shapes and geometries. This approach will also exploit the strongly confined electrical and optical excitations supported in these systems which are sensitive to boundary effects and thereby enable precisely tunable responses and new device applications. The fundamental tasks that will be addressed in this project and for which our team is uniquely positioned. -Discovery and probe of new orbitronic topological materials with Berry curvatures arising from orbital degrees of freedom. -Fabrication and manipulation of orbitronic nanomaterials using confinement, shape and morphology. -Developing new optoelectronic probes of topological states of matter. Accomplishments: 1) Discovery of spatially dispersive CPGE in Weyl semimetals (published in Nature Materials, 2019) 2) Orbitronics theory developed for systems lacking strong spin-prboit coupling (published in Physics Rev Letts, 2020) 3) Orbital photogalvanic effect discovered in Weyl semimetals (Science 2020) 4) Quadrupolar photogalvnaic effect in strongly correlated excitonic insulators discovered (published in Science Advances, 2022). 5) Formal theory for nonlinear response functions in twisted moire systems developed (m/s under preparation) Training Opportunities: graduate students and postdocs trained under this grant to design and perform optoelctronic experiments, response function nonlinear theory, data analyses and communications results to the wider scientific community.