Realization of Dirac Cones in Few Bilayer Sb(111) Films by Surface Modification

Abstract

We report the first-principle study on the recovery and linearization of Dirac cones in the electronic band structures of a few bilayer Sb(111) films (n-BL Sb) by surface modification. Due to the interaction between the surface states on the two surfaces of a free-standing film, the distorted Dirac cone in n-BL Sb(111) (n < 5) disappears. We demonstrate that the Dirac cone can be restored by functionalizing one surface with certain atoms including H, Ag, and Au, to reduce the inter-surface interaction. We further show that an ideal Dirac cone with linear dispersion of topological surface states near the zone center can be realized by functionalizing both surfaces of the film with oxygen, which enhances spin-orbital coupling. The realization of Dirac cone by surface functionalization shows promise for applications of topologic materials to spintronic devices and their operation in complicated conditions.Electronic supplementary materialThe online version of this article (doi:10.1186/s11671-015-1043-8) contains supplementary material, which is available to authorized users.

Strong coupling and periodic potential at the Pb/Sb(111) interface

“…In the moiré island the periodicity of the moiré pattern is about 1.80 ± 0.15 nm, which matches five Pb and four Sb interatomic distances (3.5 and 4.3 Å, respectively, considering free Pb(111) and Sb(111) surfaces [28,29]). It has to be noted that in several moiré islands we measured some deformations of the moiré superstructure with respect to a perfect hexagonal lattice, probably due to distortions induced by edges.…”

The topological soliton in Peierls semimetal Sb

“…Both the k-point grid and the cutoff energy were subjected to convergence testing. Structural optimization resulted in a rhombohedral structure with lattice parameters a = 4.594 Å and α = 56.96°, in agreement with the well-established structure 15 – 17 and previous ab initio calculations 18 – 21 . Along the [111] direction the interplanar distance alternates between d 1 = 1.54 Å and d 2 = 2.31 Å, corresponding to covalent and van der Waals bonding, respectively 16 , 19 , 20 , 22 , 23 , and is depicted in Fig.…”

Entanglement entropy and entanglement spectrum of Bi1−xSbx(1 1 1) bilayers

“…Robustness of topological properties of Bi(1 1 1) were recently discussed in [24][25][26]. Extensive studies have been carried out for fewlayer Bi and Sb systems [27][28][29][30]. Pure Bi(1 1 1) films up to eight bilayers in thickness were shown to exhibit a stable QSH phase [15].…”