High-Buckled Root 3 X Root 3 Stanene With A Topologically Nontrivial Energy Gap

We demonstrate an efficient way of tuning the atomic buckling in stanene to open a topologically nontrivial energy gap. By tuning the growth kinetics, we obtain an unexpected high-buckled root 3 x root 3 stanene on the Bi(111) substrate. Scanning tunneling microscopy study combined with density functional theory calculation confirms that the root 3 x root 3 stanene is a distorted 1 x 1 structure with a high-buckled Sn in every three 1 x 1 unit cells. The high-buckled root 3 x root 3 stanene favors a large band inversion at the Gamma point, and the spin-orbit coupling opens a topologically nontrivial energy gap. This study provides an alternate way to tune the topology of monolayer topological materials.