Strain-Induced Nontrivial Topology and a Negative Poisson’s Ratio in the Sn2BN Monolayer Strain-Induced Nontrivial Topology and a Negative Poisson’s Ratio in the Sn2BN Monolayer AITranslate

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DOI：https://doi.org/10.1021/acsaelm.3c00954

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Two-dimensional (2D) quantum spin Hall (QSH) insulators have attracted a great deal of attention since they enable the dissipationless transport of electrons, which serve as ideal candidates for designing miniaturized electronic devices. Here, through first-principles calculations, the Sn2BN monolayer is proved as a 2D material with excellent thermodynamic stability that can realize the QSH effect under the action of biaxial strain. Such a nontrivial topology is characterized through the band inversion related to Sn-px,y with B-pz orbitals at the Γ point induced by spin–orbit coupling (SOC) and confirmed by the Z2 invariant and gapless helical edge states. More interestingly, by employing specific tensile strain, the Sn2BN monolayer can host the characteristic of a negative Poisson’s ratio. In addition to biaxial strain, the external electric field is also an effective technique to tune the global band gap of the Sn2BN monolayer. Our findings reveal the strain-induced outstanding topological and mechanical properties in the Sn2BN monolayer, which provide a platform for designing multifunctional quantum devices.