New topological states in HgTe quantum wells from defect patterning

To explore new methods for the realization of the quantum spin Hall (QSH) effect in two-dimensional (2D) materials, we have constructed a honeycomb geometry (HG) by etching rows of hexagonal holes in HgTe quantum wells (QWs). Theoretical calculations show that multiple Dirac cones can be produced by HG, regardless of whether the band inversion occurs or not. Furthermore, the topological states originating from a narrow HG region in a wide ribbon show strong localization at the physical edges of the ribbon, making them easy to manipulate and exploit. When the band inversion condition for QW states is satisfied, the topological states generated by two different mechanisms may coexist. Our studies pave the way to produce and control multiple QSH states in 2D materials as desired for the design of innovative spintronic materials.