Robust topological edge states at the perfect surface step edge of   topological insulator ZrTe$_5$
  We report an atomic-scale characterization of ZrTe$_5$ by using scanning tunneling microscopy. We observe a bulk bandgap of ~80 meV with topological edge states at the step edge, and thus demonstrate ZrTe$_5$ is a two dimensional topological insulator. It is also found that an applied magnetic field induces energetic splitting and spatial separation of the topological edge states, which can be attributed to a strong link between the topological edge states and bulk topology. The perfect surface steps and relatively large bandgap make ZrTe$_5$ be a potential candidate for future fundamental studies and device applications. 
Xiang-Bing Li, Wen-Kai Huang, Yang-Yang Lv, Kai-Wen Zhang, Chao-Long   Yang, Bin-Bin Zhang, Y. B. Chen, Shu-Hua Yao, Jian Zh...
cond-mat.mtrl-sci