Magnetize Topological Surface States of Bi 2 Se 3 with a CrI 3 Monolayer

To magnetize surfaces of topological insulators without damaging their topological feature is a crucial step for the realization of the quantum anomalous Hall effect (QAHE), and still remains as a challenging task. Through density functional calculations, we found that adsorption of a two-dimensional van der Waals (2D-vdW) ferromagnetic insulator CrI3 monolayer can create a sizable spin splitting at the Dirac point of the topological surface states of Bi2Se3 films. Furthermore, general rules that connect different quantum and topological parameters are established through model analyses. This work provides a useful guideline for the realization of QAHE at high temperature in heterostructures of 2D-vdW magnetic monolayers and topological insulators.