Impurity-engineered Dirac nodes in three-dimensional topological insulators*

Electronic structure of Dirac materials can be manipulated by impurity doping. One example of such manipulation is the quantum anomalous Hall effect (QAHE), observed in a three-dimensional (3D) topological insulator (TI) doped with magnetic impurities. It is known that impurities give rise to low-energy resonant states near Dirac nodes [1]. For a magnetically-doped 3D TI, an energy gap opens up at the node and is filled with impurity resonant states. Impurity effects have significant implications for QAHE [2,3]. In this work, we show how doping can be used to engineer Dirac nodes in a 3D TI. Using a microscopic tight-binding model for a typical 3D TI with impurities on the surface, we demonstrate the splitting of the surface node and the appearance of new nodes at high-symmetry points of the Brillouin zone. This opens a possibility for impurity engineering of topology and nodal structure in Dirac materials.
1. Biswas, R. R. and Balatsky, A. V., Phys. Rev. B 81, 233405 (2010).
2. Black-Schaffer, A. M. et al., Phys. Rev. B 91, 201411 (2015).
3. Sessi, P. et al., Nat. Commun. 7, 12027 (2016).