Controllable band structure and topological phase transition in two-dimensional hydrogenated arsenene

Abstract

Discovery of two-dimensional (2D) topological insulator such as group-V films initiates challenges in exploring exotic quantum states in low dimensions. Here, we perform first-principles calculations to study the geometric and electronic properties in 2D arsenene monolayer with hydrogenation (HAsH). We predict a new σ-type Dirac cone related to the px,y orbitals of As atoms in HAsH, dependent on in-plane tensile strain. Noticeably, the spin-orbit coupling (SOC) opens a quantum spin Hall (QSH) gap of 193 meV at the Dirac cone. A single pair of topologically protected helical edge states is established for the edges, and its QSH phase is confirmed with topological invariant Z2 = 1. We also propose a 2D quantum well (QW) encapsulating HAsH with the h-BN sheet on each side, which harbors a nontrivial QSH state with the Dirac cone lying within the band gap of cladding BN substrate. These findings provide a promising innovative platform for QSH device design and fabrication operating at room temperature.

Two-Dimensional Large Gap Topological Insulators with Tunable Rashba Spin-Orbit Coupling in Group-IV films

“…Upon including SOC, the band structures produce a transition from semimetal to semiconductor, as the degenerated states at the touching point separate from each other, see Figs 3(a–d) and 4(b). As observed in previously reported Bi/Sb/As17181920, the SOC-induced band-gap opening at the Fermi level is a strong indication of the existence of topologically nontrivial phases. Furthermore, from Si to Pb atom, the band gap opening gradually increases (Table 1), since the SOC effect gets stronger due to increasing atomic numbers of heavier atoms.…”

“…1(b). All these configurations are iso-structural to inversion-symmetric Ge/Sn/Pb monolayers with C 3v symmetry19202122232425, but the A and B sublattices are occupied with different group-IV atoms, resulting in inversion-symmetry breaking. To verify the geometric stability of these structures, the total energies AB Cl 2 monolayers with respect to lattice constant a are illustrated in Fig.…”

“…These samples include silicene10, germanene11, stanene12, plumbene13, bismuth14, and arsenene15, in which they exhibit the topology properties alike to grapheme, but their nontrivial bulk gaps are still small. Motivated by the experimental synthesis of hydrogenated germanene (GeH)16, the chemical functionalization on honeycomb structure, e.g., Bi/Sb/As17181920 and Ge/Sn/Pb films21222324252627, has been proposed to host QSH effect with enhanced band gaps. For example, Xu et 12 reported that the nontrivial band gap of pristine stanene is merely 0.1 eV, while it is enlarged to 0.3 eV under fully halogenation1223242526.…”

“…synthesize 2D honeycomb Ge 1−x Sn x H 1−x (OH) x film from the topochemical deintercalation of CaGe 2–2x Sn 2x . In comparison with inversion-symmetric systems1516171819202122232425262728293031, the introduction of tin breaks the inversion-symmetry of 2D germanene, which may induce a significant large Rashba SOC. Motived by above suppose, we attempt to extend and advance the group-IV 2D films to realize giant Rashba SOC accompanied with nontrivial topology, which may our proposal achievable experimentally accessible.…”

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 …”