Tuning band inversion symmetry of buckled III-Bi sheets by halogenation

• Published in: Nanotechnology 2016-02, Vol.27 (5), p.055704-055704
• Main Authors: Freitas, R R Q, de Brito Mota, F, Rivelino, R, de Castilho, C M C, Kakanakova-Georgieva, A, Gueorguiev, G K
• Format: Article
• Language: English
• Subjects: bismuth-based 2D materials; Electronics; Energy gaps (solid state); Halogenation; Inversions; Nanostructure; spin-orbit coupling; Symmetry; topological insulators; Topology; Tuning
• ISSN: 0957-4484; 1361-6528; 1361-6528
• DOI: 10.1088/0957-4484/27/5/055704

First-principles calculations are employed to investigate structural, electronic and topological insulating properties of XBi (X = B, Al, Ga, and In) monolayers upon halogenation. It is known that Y-XBi (X = Ga, In, Tl; Y = F, Cl, Br, I) can originate inversion-asymmetric topological insulators with large bulk band gaps. Our results suggest that Y-XBi (X = B, Al; Y = F, Cl, Br, I) may also result in nontrivial topological insulating phases. Despite the lower atomic number of B and Al, the spin-orbit coupling opens a band gap of about 400 meV in Y-XBi (X = B, Al), exhibiting an unusual electronic behavior for practical applications in spintronics. The nature of the bulk band gap and Dirac-cone edge states in their nanoribbons depends on the group-III elements and Y chemical species. They lead to a chemical tunability, giving rise to distinct band inversion symmetries and exhibiting Rashba-type spin splitting in the valence band of these systems. These findings indicate that a large family of Y-XBi sheets can exhibit nontrivial topological characteristics, by a proper tuning, and open a new possibility for viable applications at room temperature.