Topological insulators (TIs) are a recently discovered class of materials having insulating bulk electronic states but conducting boundary states distinguished by nontrivial topology. So far, several generations of TIs have been theoretically predicted and experimentally confirmed, all based on inorganic materials. In this talk, I will present our recent study of a family of two-dimensional organic TIs made of organometallic lattices, based on first-principles calculations and tight-binding model analyses. Designed by assembling molecular building blocks of organometallic compounds with strong spin-orbit coupling into a hexagonal and Kagome lattices, these new classes of organic TIs are shown to exhibit nontrivial topological edge states in both Dirac bands and flat Chen bands, which are robust against significant lattice strain. Realization of anomalous quantum Hall effect in magnetic organic TIs with the inclusion of transition metal elements will also be discussed. We envision that organic topological materials will greatly broaden the scientific and technological impact of topological materials.
Dr. Zhengfei Wang received his B.S. degree from Henan Normal University in 2003, and obtained his Ph.D. in Condensed Matter Physics at University of Science and Technology of China in 2008. Currently, he is a Postdoctoral fellow at University of Utah. He has published 33 papers with more than 1000 citations, including 1 Nature Materials, 2 Nature Communications, 1 PNAS, 5 Physical Review Letters and 3 Nano Letters. His main research interests are electronic structure and transport calculations in low-dimensional materials.