Strain can be used as an effective tool to tune the crystal structure of materials and hence to modify their electronic structures, including topological properties. Here, taking Na3Bi as a paradigmatic example, we demonstrated with first-principles calculations and k⋅p models that the topological phase transitions can be induced by various types of strains. For instance, the Dirac semimetal phase of ambient Na3Bi can be tuned into a topological insulator (TI) phase by uniaxial strain along the h100i axis. Hydrostatic pressure can let the ambient structure transfer into a new thermodynamically stable phase with Fm-3m symmetry, coming with a perfect parabolic semimetal having a single contact point between the conduction and valence bands, exactly at Γ point on the Fermi level like α-Sn. Furthermore, uniaxial strain in the <100> direction can tune the new parabolic semimetal phase into a Dirac semimetal, while shear strains in both the <100> and <111> directions can take the new parabolic semimetal phase into a TI. k⋅p models are constructed to gain more insights into these quantum topological phase transitions. At last, we calculated surface states of Fm-3m Na3Bi without and with strains to verify these topological transitions.
@article{arxiv.1708.04094,
title = {Strain-induced quantum topological phase transitions in Na3Bi},
author = {Dexi Shao and Jiawei Ruan and Juefei Wu and Tong Chen and Zhaopeng Guo and Haijun Zhang and Jian Sun and Li Sheng and Dingyu Xing},
journal= {arXiv preprint arXiv:1708.04094},
year = {2017}
}