Controlling Topological States in Topological/Normal Insulator Heterostructures

We
have performed a systematic investigation of the nature of the
nontrivial interface states in topological/normal insulator (TI/NI)
heterostructures. On the basis of first principles and a recently
developed scheme to construct ab initio effective Hamiltonian matrices
from density functional theory calculations, we studied systems of
realistic sizes with high accuracy and control over the relevant parameters
such as TI and NI band alignment, NI gap, and spin–orbit coupling
strength. Our results for IV–VI compounds show the interface
gap tunability by appropriately controlling the NI thickness, which
can be explored for device design. Also, we verified the preservation
of an in-plane spin texture in the interface-gaped topological states.