Strain-dependent electronic and mechanical properties in one-dimensional topological insulator Nb4SiTe4

Topological insulators hold great promise for dissipationless transport devices due to the robust gapless states inside the insulating bulk gap. So far, several generations of topological insulators have been theoretically predicted and experimentally confirmed, most of them based on three- or two-dimensional materials. Here, on the basis of the first-principles calculations, we predict a quasi-one-dimensional (quasi-1D) topological insulator ${\mathrm{Nb}}_{4}{\mathrm{SiTe}}_{4}$ that can be prepared by exfoliation from its three-dimensional bulk phase. This material, characterized by topological ${\mathbb{Z}}_{2}$ invariants and robust zero-energy edge states, has a large nontrivial gap of $\ensuremath{\sim}93.6$ meV, large enough for inhibiting the possibility of the thermal disturbance. Additionally, when applying pressure, we find there is an abnormal force releasing stage originating from the shrinking of the inner Nb atomic rings. In addition, we find that substrate, stacking, defect, and structure deformation have specific effects on electronic properties. Our results reveal a promising quasi-1D topological insulator ${\mathrm{Nb}}_{4}{\mathrm{SiTe}}_{4}$ and uncover its unique strain-dependent electronic and mechanical properties.