The origin of electronic band structure anomaly in topological crystalline insulator group-IV tellurides

Researchers in China and the USA offer an explanation for why some materials are semiconductors while others exhibit more exotic behavior. Jun-Wei Luo from the Institute of Semiconductors, Chinese Academy of Sciences, and collaborators used first-principles calculations to model the electronic band structure of three related binary compounds: germanium telluride, tin telluride and lead telluride. Germanium, tin and lead are all in the same column on the periodic table, so their properties would be expected to be similar, varying as a function of atomic number. In reality, however, these compounds exhibit starkly different behaviors. Luo and colleagues found explanations for these differences through symmetry analysis and in atomic energy levels and sizes. These findings offer a new solution to this previously unexplained anomaly, and pave the way for more effective engineering of topological insulators.