Reorganization of the topological surface mode of topological insulating α-Sn

Rui Tan; Qi Qi; Peng Wang; Yanqiang Cao; Rongrong Si; Maoxiang Wang; Xiaoxiong Wang

doi:10.1088/1361-648X/ac3c65

Reorganization of the topological surface mode of topological insulating α-Sn

J Phys Condens Matter. 2021 Dec 9;34(9). doi: 10.1088/1361-648X/ac3c65.

Authors

Rui Tan¹, Qi Qi¹, Peng Wang², Yanqiang Cao^{1

3}, Rongrong Si¹, Maoxiang Wang¹, Xiaoxiong Wang^{1

3}

Affiliations

¹ Department of Applied Physics, Nanjing University of Science and Technology, Nanjing 210094, People's Republic of China.
² College of Electronic, Communication and Physics, Shandong University of Science and Technology, Qingdao 266590, People's Republic of China.
³ MIIT Key Laboratory of Semiconductor Microstructure and Quantum Sensing, Nanjing University of Science and Technology, Nanjing 210094, People's Republic of China.

PMID: 34814131
DOI: 10.1088/1361-648X/ac3c65

Abstract

α-Sn is a topologically nontrivial semimetal in its natural structure. Upon compressively strained in plane, it transforms into a topological insulator. But, up to now, a clear and systematic understanding of the topological surface mode of topological insulating α-Sn is still lacking. In the present work, first-principle simulations are employed to investigate the electronic structure evolution of Ge_1-xSn_xalloys aiming at understanding the band reordering, topological phase transition and topological surface mode of α-Sn in detail. Progressing from Ge to Sn with increasing Sn content in Ge_1-xSn_x, the conduction band inverts with the first valence band (VB) and then with the second VB sequentially, rather than inverting with the latter directly. Correspondingly, a topologically nontrivial surface mode arises in the first inverted band gap. Meanwhile, a fragile Dirac cone appears in the second inverted band gap as a result of the reorganization of the topological surface mode caused by the first VB. The reorganization of the topological surface mode in α-Sn is very similar to the HgTe case. The findings of the present work are helpful for understanding and utilizing of the topological surface mode of α-Sn.

Keywords: first-principles; reorganization; topological surface mode; α-Sn.