标题： 通过体-边对应关系识别拓扑激子绝缘体 显示英文标题

标题： Identifying topological excitonic insulators via bulk-edge correspondence

摘要： 激子绝缘体仍然难以捉摸，且缺乏可靠的识别方法。 在本工作中，我们展示了拓扑激子绝缘体在识别方面的前景，因为它们具有独特的体-边对应关系，如LiFe$X$ ($X$ = S, Se, 和 Te) 家族所示。 第一性原理Bethe-Salpeter方程计算揭示了这些自旋轨道耦合量子反常霍尔绝缘体中的激子不稳定性。 有效哈密顿量分析表明，自发激子凝聚不会破坏无能隙的边缘态，而是将体能隙重构为几乎与自旋轨道耦合强度无关。 这种体-边对应关系的变化可以通过角分辨光电子能谱或电子压缩性测量进行实验检测，为拓扑激子绝缘体的识别提供了观察证据。 此外，激子凝聚将拓扑非平凡相的临界温度提高到了室温以上。 显示英文摘要

摘要： Excitonic insulator remains elusive and there has been a lack of reliable identification methods. In this work, we demonstrate the promise of topological excitonic insulators for identification due to their unique bulk-edge correspondence, as illustrated by the LiFe$X$ ($X$ = S, Se, and Te) family. First-principles Bethe-Salpeter equation calculations reveal excitonic instabilities in these spin-orbit coupling quantum anomalous Hall insulators. Effective Hamiltonian analyses indicate that spontaneous exciton condensation does not disrupt the gapless edge state but reconstructs the bulk-gap to be almost independent of the spin-orbit coupling strength. This change in the bulk-edge correspondence can be experimentally inspected by angle-resolved photoelectron spectroscopy or electron compressibility measurements, providing observational evidence for the identification of topological excitonic insulators. Moreover, exciton condensation raises the critical temperature of the topological nontrivial phase above room temperature.