三维拓扑结构：大角度扭转石墨中堆叠控制的Umklapp散射
Three-Dimensional Topology from Stacking-Controlled Umklapp Scattering in Large-Angle Twisted Graphite
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中文总结 AI 辅助
本研究通过对称性约束有效模型和DFT计算，揭示大角度扭转石墨中堆叠控制的Umklapp散射可产生节线相和高阶拓扑绝缘体，压缩可驱动其转变为Weyl半金属，为三维扭转结构拓扑工程提供新途径。
中文摘要 AI 辅助
大角度扭转石墨烯超出了传统莫尔系统中局部堆叠描述的范围：不等价的旋转中心定义了不同的共度界面，其低能层间杂化由谷间Umklapp隧穿控制。对于由不同晶体对称性界面组装的三维扭转石墨，一个对称性约束的有效模型揭示了非手性和手性隧穿之间的竞争产生了单环和双环节线相，以及在子格（手性）对称性存在下的$C_3$保护的高阶拓扑绝缘体。节线环携带整数绕数，允许相反绕向的环湮灭进入有隙相。我们进一步研究了子格对称性破缺如何修改这些相。针对$21.8^\circ$扭转石墨的密度泛函理论（DFT）和原子计算确定了平衡结构为高阶拓扑绝缘体，而压缩则驱动其进入拓扑Weyl半金属相。这些发现确立了对称性不等价界面的堆叠顺序作为在三维扭转结构中工程化能带拓扑的一种手段。
英文摘要
Large-angle twisted graphene lies beyond the local-stacking description of conventional moiré systems: inequivalent rotation centers define distinct commensurate interfaces whose low-energy interlayer hybridization is governed by intervalley Umklapp tunneling. For three-dimensional twisted graphite assembled from interfaces with different crystalline symmetries, a symmetry-constrained effective model reveals that competition between nonchiral and chiral tunneling produces one-ring and two-ring nodal-line phases and a $C_3$-protected higher-order topological insulator in the presence of sublattice (chiral) symmetry. The nodal rings carry integer winding numbers, allowing oppositely wound rings to annihilate into the gapped phase. We further examine how sublattice-symmetry breaking modifies these phases. Density functional theory (DFT) and atomistic calculations for $21.8^\circ$ twisted graphite identify the equilibrium structure as a higher-order topological insulator, while compression drives it into a topological Weyl semimetal phase. These findings establish the stacking sequence of symmetry-inequivalent interfaces as a means of engineering band topology in three-dimensional twisted structures.
发表机构
- Beihang University（北京航空航天大学）
- University of Hong Kong（香港大学）
机构由 AI 辅助整理，请以论文原文为准。
