在BHZ超晶格中调控竞争性分数拓扑态

中文摘要 AI 辅助

标量超晶格为从简单拓扑带走向分数化态提供了一条途径，而多组分系统则提出了另一个问题：哪种分数阶在能量上被优先选择。我们证明，将标量超晶格应用于Qi-Wu-Zhang（QWZ）陈绝缘体模型，会产生一个孤立的C = +1微带，其Berry曲率和量子度量的均匀性得到显著改善。对投影相互作用的精确对角化在该微带中识别出一个1/3分数陈绝缘体。恢复时间反演伙伴以形成Bernevig-Hughes-Zhang（BHZ）超晶格，在总填充为2/3时，产生一个平衡的分数量子自旋霍尔（FQSH）类态和一个完全极化的2/3分数陈绝缘体。它们的竞争将分数态控制的两个方面区分开来：有限动量分量间耦合决定了平衡FQSH类态的稳定性，而均匀的赝自旋各向异性则改变了守恒扇区的相对能量，并能在平衡态和极化态之间切换全局基态。这些结果建立了一个最小晶格设置，将拓扑微带重构、分数态形成和分数态选择联系起来，展示了如何结合不同层次的控制来导航竞争性的分数拓扑态。

英文摘要

Scalar superlattices offer a route from simple topological bands to fractionalized states, while multicomponent systems raise the additional question of which fractional order is energetically selected. We show that a scalar superlattice applied to the Qi-Wu-Zhang (QWZ) Chern-insulator model produces an isolated C = +1 miniband with strongly improved Berry-curvature and quantum metric uniformity. Exact diagonalization of the projected interaction identifies a 1/3 fractional Chern insulator in this miniband. Restoring the time-reversed partner to form the Bernevig-Hughes-Zhang (BHZ) superlattice yields, at total filling 2/3, a balanced fractional quantum spin Hall (FQSH)-like state and a fully polarized 2/3 fractional Chern insulator. Their competition separates two aspects of fractional-state control: the finite-momentum intercomponent coupling governs the stability of the balanced FQSH-like state, whereas a uniform pseudospin anisotropy shifts the relative energies of conserved sectors and can switch the global ground state between the balanced and polarized states. These results establish a minimal lattice setting that connects topological-miniband reconstruction, fractional-state formation, and fractional-state selection, illustrating how distinct levels of control can be combined to navigate competing fractional topological states.

发表机构

• Lanzhou University（兰州大学）

机构由 AI 辅助整理，请以论文原文为准。