Two-Dimensional Group-IV Chalcogenide Si2Te2 film: A New Quantum Spin Hall Insulator with Sizable Band Gap

Abstract

Quantum spin Hall (QSH) effect is promising for achieving dissipationless transport devices due to the robust gapless states inside insulating bulk gap. Here, by using first-principles calculations, we discover group-IV chalcogenide Si2Te2 film to be a 2D QSH insulator with a fundamental band gap of 0.29 eV, which is tunable under external strain. This nontrivial topological phase stems from band inversion between the Si-px,y and Te-px,y orbitals, demonstrated by a single pair of topologically protected helical edge states with Dirac point locating in the bulk gap. Notably, the characteristic properties of edge states, such as the Fermi velocity and edge shape, can be tuned by edge modifications. Additionally, the h-BN semiconductor is an ideal substrate for experimental realization of 2D Si2Te2 film, without destroying its nontrivial topology. Our works open a new route for designing topological spintronics devices based on 2D silicon-based films.

18 pages, 6 figures

References in corpus (5)

• Quantum Spin Hall Effect and Topological Phase Transition in HgTe Quantum Wells
• Quantum Spin Hall Insulator State in HgTe Quantum Wells
• Quantum Spin Hall Effect in Inverted Type II Semiconductors
• Epitaxial growth of large-gap quantum spin Hall insulator on semiconductor surface
• Majorana Fermions: The race continues

Cited by in corpus (4)

• Discovery of Intrinsic Quantum Anomalous Hall Effect in Organic Mn-DCA Lattice
• Quantization of spin Hall conductivity in two-dimensional topological insulators versus symmetry and spin-orbit interaction
• Two-Dimensional Large Gap Topological Insulators with Large Rashba Spin-Orbit Coupling in Group-IV films
• Prediction of Topological Crystalline Insulator and Topological Phase Transitions in Two-dimensional PbTe Films