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arXiv 2204.06641cond-mat.mes-hallcond-mat.str-el
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在一个 $C_3$ 对称性破缺模型中具有偶数和奇数对零能角模的多种高阶拓扑相

Multiple higher-order topological phases with even and odd pairs of zero-energy corner modes in a $C_3$ symmetry broken model

Sudarshan Saha, Tanay Nag, Saptarshi Mandal

AI总结:

研究扩展 Haldane 模型中 $C_3$ 对称性破缺下的高阶角模,揭示子晶格质量、Zeeman 场与 SOC 竞争如何调控零能偶极态简并及 SOT 相。

摘要:

近来,人们已在 $C_3$ 对称性破缺的蜂窝晶格中设计了量子反常霍尔绝缘体的高阶角模。这里,我们考虑一个扩展 Haldane 模型,其中存在反演对称性破缺的子晶格质量、时间反演对称性破缺的 Zeeman 场以及自旋轨道耦合相互作用;我们发现,只有量子自旋霍尔绝缘体能够承载二阶偶极相,而其余两个一阶拓扑相不会演变为后者。值得注意的是,当自旋轨道耦合已经存在时,通过施加(撤去)子晶格质量(Zeeman 场)项,零能偶极态的四重简并可降为二重简并。另一方面,在不存在或存在自旋轨道耦合时,子晶格质量项与 Zeeman 场项相互竞争,将两个中隙态钉扎在零能处。有趣的是,只要反演对称性得到保持,无论中隙态的能量如何,体极化都可对偶极相进行拓扑表征。有效能隙判据能够定性模拟由有限 Zeeman 交换场、子晶格质量和 SOC 相互作用之间的相互作用所产生的 SOT 相的范围。

英文摘要:

The higher-order corner modes for quantum anomalous Hall insulators in $C_3$ symmetry broken honeycomb lattice have been engineered recently. Here we consider an extended Haldane model in presence of inversion symmetry breaking sub-lattice mass, time-reversal symmetry breaking Zeeman field and spin-orbit coupling interaction where we find that only the quantum spin Hall insulator can host the second-order dipolar phase while the remaining two first-order topological phases do not morph into the latter. Remarkably, four-fold degeneracy of zero-energy dipolar states can be reduced to two-fold under the application (withdrawn) of sub-lattice mass (Zeeman field) term when the spin-orbit coupling is already present. On the other hand, the sub-lattice mass and Zeeman field terms compete with each other to pin down the two mid-gap states at zero-energy in the absence or presence of spin-orbit coupling. Interestingly, the bulk-polarization can topologically characterize the dipolar phase irrespective of the energy of the mid-gap states as long as inversion symmetry is preserved. The effective gap criterion can qualitatively mimic the extent of SOT phase originated by the interplay between finite Zeeman exchange field, sub-lattice mass, and SOC interaction.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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