Theoretical investigation of the HgTe topological edge states with a Fe impurity

The robustness of the Dirac-like states in topological insulators depends on the preservation of the time-reversal symmetry. A magnetic impurity can locally break this symmetry and destroy the protected edge states. However, it is not clear how the influence of this symmetry breaking field depends on the distance between the edge structures (surface or interface) and the magnetic impurity. In this work we use the density functional theory to study the properties of the HgTe/CdTe (001) interface and the (001) HgTe surface in the presence of a Fe impurity. Our results show that for a Fe impurity in the HgTe/CdTe, the spin polarization in the edge states decreases due to the coupling between the magnetic moment of impurity and the magnetic moment of heterostructure, inducing an out-of-plane spin polarization at the interface or surface.