posted on 2024-01-04, 17:05authored byKunyue Shi, Didi Zhao, Shengshi Li, Weixiao Ji, Changwen Zhang, Peiji Wang
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.