Two-dimensional arsenene oxide: A realistic large-gap quantum spin Hall insulator

Abstract

Searching for two-dimensional (2D) realistic materials able to realize room-temperature quantum spin Hall (QSH) effects is currently a growing field. Here, we through ab initio calculations to identify arsenene oxide, AsO, as an excellent candidate, which demonstrates high stability, flexibility, and tunable spin-orbit coupling (SOC) gaps. In contrast to known pristine or functionalized arsenene, the maximum nontrivial band gap of AsO reaches 89 meV, and can be further enhanced to 130 meV under biaxial strain. By sandwiching 2D AsO between BN sheets, we propose a quantum well in which the band topology of AsO is preserved with a sizeable band gap. Considering that AsO having fully oxidized surfaces are naturally stable against surface oxidization and degradation, this functionality provides a viable strategy for designing topological quantum devices operating at room temperature.One of the grand challenges in condensed matter physics and materials science is to develop dissipationless electron conduction operating at room temperature. The appearance of band topology opens the door to fields of topological quantum states (TQSs), e.g., topological Dirac semimetal 1,2 , Weyl semimetal 3,4 , and node-line semimetal 5,6 , as well as topological insulators (TIs) 7 and so on.Remarkably, two-dimensional (2D) TIs hosts quantum spin Hall (QSH) effect with one-dimensional helical edge states, which can serve as a "two-lane highway" protected by time-reversal symmetry (TRS), making it more suited for coherent spin transport than 3D TIs. 8,9 However, the * Corresponding author: C. W. Zhang: ss_zhangchw@ujn.edu.cn experimental observations of quantized Hall conductance through QSH effect are only reported in HgTe/CdTe 10,11 and InAs/GaSb 12,13 quantum-wells with a ultralow temperature (<10 K). Hence considerable effort has been devoted to design new materials with QSH effect, and a variety of large-gap 2D TIs have been proposed, including the honeycomb lattices of silicene, 14,15 germanene, 16,17 stanene, 18-21 plumbene, 22 transition-metal halide 23 , ZrTe 5 /HfTe 5 24 , III-V bilayers 25 , BiF 26 , and Bi/Sb 27 , but none of them has been directly confirmed in experiments. Searching for realistic 2D TIs with large gap that can support high-temperature applications is vitally essential.

Theoretical studies on tunable electronic structures and potential applications of two‐dimensional arsenene‐based materials

“…Such planarization could induce unique electronic properties. The functionalized arsenene AsR nanosheets, which are terminally decorated with R=H, F, Cl, Br, I, O, OH, CH 3 , etc, have aroused particular interests …”

“…More recently, the arsenene oxide was theoretically predicated to have excellent stability and electronic structural flexibility. The maximum bandgap of AsO was reported to be 89 meV, which can be increased to 130 meV by applying a biaxial strain . In fact, the functionalized materials should be integrated into nanodevices, and the film must be deposited on an appropriate substrate in experiments.…”

“…In fact, the functionalized materials should be integrated into nanodevices, and the film must be deposited on an appropriate substrate in experiments. Figure a has illustrated the complex structures of the 2D AsO material on the BN sheet, bearing 4.96% lattice mismatch for the h ‐BN substrate . Shown in Figure b is the electronic structure of the AsO/h‐BN heterostructure with the application of 6% tensile strain.…”

“…(c) Schematic illustration for the BN/AsO/BN heterostructure. (Reprinted with permission from Reference . Copyright 2017 American Physical Society)…”

“…The functionalized arsenene AsR nanosheets, which are terminally decorated with R=H, F, Cl, Br, I, O, OH, CH 3 , etc, have aroused particular interests. [65][66][67][68][69][70][71][72][73][74][75][76][77] The electronic structures of halogenated arsenenes were predicted to be stable via formation energy calculations, except AsI monolayer. The Dirac cone was found to appear in the halogenated arsenenes, 68,69 probably due to flattening of the structures of monolayer arsenenes upon fluorination.…”