Twist-induced quantum valley Hall states in bilayer germanene

作者：Yuhao Shen, Jun‐Ding Zheng, Wen‐Yi Tong, Zhi-qiang Bao, Xiangang Wan, Chun‐Gang Duan · 发表于：Physical review. B./Physical review. B · 年份：2025 · DOI：10.1103/physrevb.111.075421 · 被引用次数：5 · 研究领域：Topological Materials and Phenomena、Graphene research and applications、Quantum and electron transport phenomena

In van der Waals bilayer germanene, we show a twist-induced nontrivial topological transition and find it can host the quantum valley Hall effect (QVHE). It is demonstrated that band inversion is induced at each $K$ of the supercell Brillouin zone (SBZ). The topological phase transition comes from the fact that the valley Chern number, ${C}_{v}={C}_{K}\ensuremath{-}{C}_{{K}^{\ensuremath{'}}}$, switches from 0 to 2, which characterizes the nontrivial QVHE phase. Taking into account spin-orbit coupling (SOC), this band topology of the moir\'e superlattice originates from both the low-buckled structure within each layer and the coexistence of distinct stacking domains---namely, AA, AB, and BA regions---in the bilayer, particularly for small twist angles. Our findings advance potential applications for device design in topological valleytronics and twistronics.