Towards Layer-Selective Quantum Spin Hall Channels in Weak Topological Insulator Bi4Br2I2

Abstract

Weak topological insulators, constructed by stacking quantum spin Hall insulators with weak interlayer coupling, offer promising quantum electronic applications through topologically nontrivial edge channels. However, the currently available weak topological insulators are stacks of the same quantum spin Hall layer with translational symmetry in the out-of-plane direction, leading to the absence of the channel degree of freedom for edge states. Here, we study a candidate weak topological insulator, Bi4Br2I2, which is alternately stacked by three different quantum spin Hall insulators, each with tunable topologically non-trivial edge states. Our angle-resolved photoemission spectroscopy and first-principles calculations show that an energy gap opens at the crossing points of different Dirac cones correlated with different layers due to the interlayer interaction. This is essential to achieve the tunability of topological edge states as controlled by varying the chemical potential. Our work offers a perspective for the construction of tunable quantized conductance devices for future spintronic applications.

References in corpus (10)

• Quantum Spin Hall Effect and Topological Phase Transition in HgTe Quantum Wells
• Topological Insulators with Inversion Symmetry
• Large-Gap Quantum Spin Hall Insulator in single layer bismuth monobromide Bi${}_4$Br${}_4$
• Evidence for a Strong Topological Insulator Phase in $\mathrm{ZrT}{\mathrm{e}}_5$
• Prediction of weak topological insulators in layered semiconductors
• Observation and control of the weak topological insulator state in ZrTe5
• Room-Temperature Topological Phase Transition in Quasi-One-Dimensional Material Bi${}_4$I${}_4$
• Crossed Luttinger Liquid Hidden in a Quasi-two-dimensional Material η-Mo4O11
• Quantum transport properties of beta-Bi4I4 near and well beyond the extreme quantum limit
• Large-Gap Quantum Spin Hall State and Temperature-Induced Lifshitz Transition in Bi4Br4