Topological states ruled by stacking faults in Bi2Se3 and Bi2Te3

Abstract

tended defects like stacking faults (SF) can originate topologically protected metallic states in bulk topological insulators (TI). These induced topological states are a response to the weakening of the inter-layer van der Waals interactions due to the SF defect. In TI thin films the degeneracy of Dirac bands of opposite surfaces can be lifted upon the formation of SF defects. Such slab asymmetry can promote a net spin current, absent of backscattering processes, in thin film made of TIs. These results have been obtained by fully relativistic first principles calculations.1 The authors acknowledge financial support from CNPq/INCT, CAPES, FAPEMIG, and FAPESP, and the computational support from CENAPAD/SP.

Suppressing Twin Formation in Bi2Se3 Thin Films

“…It is worth mentioning that inside a QL layer the ccp arrangement is preserved. Recently, density‐functional theory (DFT) calculations have been used to show that the presence of stacking faults in Bi 2 Se 3 layers, which lead to the appearance of different polymorphs, can influence topological properties …”

Vertical twinning of the Dirac cone at the interface between topological insulators and semiconductors

“…Interactions between ion cores and valence electrons are described by the projector-augmented wave method 25,27 . The exchange-correlation functional was in local density approximation 28 parameterized by Perdew-Zunger 29 due to agreement with experimental bond lengths among Bi 2 Se 3 quintuple layers 30 . Electronic band structures and spin textures required non-collinear spin polarizations for spin-orbit interactions.…”

Tight-binding model for the band dispersion in rhombohedral topological insulators over the whole Brillouin zone

“…Figure 6a show the effect of an electric field of E = 5 × 10 −3 V/Å on a thin film of N QL = 9. Another band engineering strategy has been suggested by ab-initio atomistic investigations on the role played by extended defects, like stacking faults, on the structural and electronic properties of 3D topological insulators 23 . In R3m structures the typical stacking is a ABCABC configuration, that is, each QL is rotated with respect to its adjacent QL by 120 o .…”