Structural and electronic properties of the Bi_1-xSb_x mono-layers

Mono-layer free Bi (Bismuthene) and Sb (Antimonene) are graphene like structures which are, in contrast with the planar graphene and hexagonal B-N, buckled additionally (hexagonal \beta-phase) due to their strong spin-orbit-coupling. This buckling enables both materials to have electronically non-trivial properties as a function of electric field and planar bi-axial strain. In the case of mono-atomic layers, the transitions between the structural phases of these materials have been extensively studied before using first principle calculation as a function of the electric field, doping and applied strain[1-4]. In topological materials one of the challenges to address in the device applications is the difficulty in controllably separating the electronic response of the topologically non-trivial states from the trivial ones. For instance, the bulk alloys Bi_1-xSb_x have been extensively studied in this scope for various compositions 0 < x < 1. In this work, we extend this idea to the Bi_1-xSb_x alloy monolayers and study using DFT the contribution of the 2D bulk and the edge states for various compositions of x. We also examine the single and twin boundaries of these mono-layers in the scope of the interface states and their topological properties.

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[2] Jianping Ji, Xiufeng Song, Jizi Liu, Zhong Yan, Chengxue Huo, Shengli Zhang, Meng Su, Lei Liao, Wenhui Wang, Zhenhua Ni, Yufeng Hao and Haibo Zeng, Nat. Comm. {\bf 7}, 13352 (2016).

[3] Feng-Chuan Chuang, Chia-Hsiu Hsu, Chia-Yu Chen, Zhi-Quan Huang, Vidvuds Ozolins, Hsin Lin, and Arun Bansil, Appl. Phys. Lett. {\bf 102}, 022424 (2013)

[4] Chia-Hsiu Hsu, Zhi-Quan Huang, Feng-Chuan Chuang, Chien-Cheng Kuo, Yu-Tzu Liu, Hsin Lin and Arun Bansil, New J. Phys. {\bf 17} 025005 (2015).