Issue 25, 2022

Quantum spin Hall effect in tilted penta silicene and its isoelectronic substitutions

Abstract

Silicene, a competitive two-dimensional (2D) material for future electronic devices, has attracted intensive attention in condensed matter physics. Utilizing an adaptive genetic algorithm (AGA), we identify a topological allotrope of silicene, named tilted penta (tPenta) silicene. Based on first-principles calculations, the geometric and electronic properties of tPenta silicene and its isoelectronic substitutions (Ge, Sn) are investigated. Our results indicate that tPenta silicene exhibits a semimetallic state with distorted Dirac cones in the absence of spin-orbit coupling (SOC). When SOC is considered, it shows semiconducting behavior with a gap opening of 2.4 meV at the Dirac point. Based on the results of Image ID:d2cp01390h-t1.gif invariant (Image ID:d2cp01390h-t2.gif = 1) and the helical edge states, we demonstrate that tPenta silicene is a topological insulator. Furthermore, the effect of isoelectronic substitutions on tPenta silicene is studied. Two stoichiometric phases, i.e., tPenta Si0.333Ge0.667 and tPenta Si0.333Sn0.667 are found to retain the geometric framework of tPenta silicene and exhibit high stabilities. Our calculations show that both tPenta Si0.333Ge0.667 and tPenta Si0.333Sn0.667 are QSH insulators with enlarged band gaps of 32.5 meV and 94.3 meV, respectively, at the HSE06 level, offering great potential for practical applications at room temperature.

Graphical abstract: Quantum spin Hall effect in tilted penta silicene and its isoelectronic substitutions

Supplementary files

Article information

Article type
Paper
Submitted
24 Mar 2022
Accepted
03 May 2022
First published
04 May 2022

Phys. Chem. Chem. Phys., 2022,24, 15201-15207

Quantum spin Hall effect in tilted penta silicene and its isoelectronic substitutions

L. Zhan, Y. Fang, R. Zhang, X. Lu, T. Lü, X. Cao, Z. Zhu and S. Wu, Phys. Chem. Chem. Phys., 2022, 24, 15201 DOI: 10.1039/D2CP01390H

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