Tunable quantum order in bilayer Bi₂Te₃: Stacking dependent quantum spin Hall states

Recent years have seen the rising importance of interface stacking in determining the electronic properties of multilayer materials stemming from the interlayer coupling; however, the stacking effects on exotic topological quantum orders largely remain to be explored. Here, we show by first-principles studies that bilayer Bi₂Te₃ host stacking is dependent on quantum spin Hall effects, with a topological phase transition induced by a change in the interlayer stacking pattern. The spin-filtered helical edge states are concomitantly switched on/off along with the changing interlayer stacking pattern. Since few-layer Bi2Te₃ has already been experimentally synthesized, the present finding opens an avenue for exploring the fundamental mechanisms and the practical implications of the quantum phenomena associated with band topology in this versatile and intriguing 2D material.