Robust large-gap quantum spin Hall insulators in methyl-functionalized III-Bi buckled honeycombs
Abstract
Based on first-principles calculations, we predict that the methyl-functionalized III-Bi monolayers, namely III-Bi-(CH3)2 (III = Ga, In, Tl) films, own quantum spin hall (QSH) states with band gaps as large as 0.260, 0.304, and 0.843 eV, respectively, making them suitable for room-temperature applications. The topological characteristics are confirmed by s -px ,y band inversion, topological invariant Z2, and topologically protected edge states. Noticeably, for GaBi/InBi-(CH3)2, the s -px ,y band inversion occurred in the process of spin-orbital coupling (SOC), while for TlBi (CH3 )2, the s -px ,y band inversion happened in the process of chemical bonding. Significantly, the nontrivial topological states in III-Bi-(CH3)2 films are robust against the mechanical strain and various methyl coverage, making them particularly flexible to substrate choice for device applications. Besides, we find the h -BN is an ideal substrate for III-Bi-(CH3)2 films to realize large-gap nontrivial topological states. These findings demonstrate that the methyl-functionalized III-Bi films may be good QSH effect platforms for topological electronic devices design and fabrication in spintronics.
- Publication:
-
Physical Review Materials
- Pub Date:
- January 2018
- DOI:
- 10.1103/PhysRevMaterials.2.014005
- arXiv:
- arXiv:1707.07120
- Bibcode:
- 2018PhRvM...2a4005L
- Keywords:
-
- Condensed Matter - Materials Science
- E-Print:
- Phys. Rev. Materials 2, 014005 (2018)