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.
Highlights
There is a great interest in searching for new quantum spin Hall (QSH) insulators in 2D materials with controllable quantum phase transitions and tunable electronic and spin properties
We propose a QW encapsulating HAsH between the BN sheet on each side, maintaining a nontrivial QSH state with the Dirac cone lying within the band gap of cladding BN substrate
Hydrogenation has been proven to be an efficient way in engineering the electronic properties in 2D materials[10,26,27,28,29,30,31,32]
Summary
There is a great interest in searching for new QSH insulators in 2D materials with controllable quantum phase transitions and tunable electronic and spin properties. An approach to design a large-gap QSH state on a semiconductor surface by a substrate orbital selection process is proposed[12]. These demonstrate that OFE is an effective way to enhance QSH effect in 2D materials with s and p orbitals dominating the conduction and valence bands. We propose a QW encapsulating HAsH between the BN sheet on each side, maintaining a nontrivial QSH state with the Dirac cone lying within the band gap of cladding BN substrate. These results provide an ideal platform for development of high-performance electronic devices in spintronics
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