发表机构
The University of Hong Kong; Universit́e Grenoble Alpes（香港大学; 格勒诺布尔阿尔卑斯大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文通过密度矩阵重整化群研究平带Haldane模型与Holstein声子耦合，发现声子将激子和磁旋子修饰为极化子模式，其软化预示电荷序，并增强引力子手征性亏损，为CI和FCI的不稳定性提供统一激发图像。
AI 中文摘要
强电子-声子耦合可能破坏陈绝缘体（CIs）和分数量子霍尔绝缘体（FCIs）的稳定性，促使其转变为电荷有序态，但CI和FCI中的不稳定性是否共享共同的微观机制仍不清楚。在本文中，我们通过研究耦合到动力学Holstein声子的平带Haldane模型在整数和分数填充下的行为来回答这一问题，采用局域基优化的密度矩阵重整化群方法。我们发现声子的低能效应主要体现为对电荷中性集体模式的修饰。在CI和FCI中，声子将激子和磁旋子修饰为复合模式，我们分别将其识别为激子极化子和磁旋子极化子。这些模式在接近转变时显著软化，而其能量最小值的动量预示了电荷有序相的序波矢。相应地，声子谱获得了从激子和磁旋子模式继承的色散特征，为这些中性激发提供了直接的晶格信号。在FCI相内，电子-声子耦合还增强了引力子响应的相反手征性谱权重，从而导致手征性亏损。我们的结果为CI和FCI中声子驱动的不稳定性提供了统一的基于激发的图像，并将晶格动力学确立为探测其中性集体模式的手段。
英文摘要
Strong electron-phonon coupling can destabilize both Chern insulators (CIs) and fractional Chern insulators (FCIs) in favor of charge order, but whether the instabilities in CI and FCI share a common microscopic mechanism remains unclear. In this paper, we address this question by studying a flat-band Haldane model coupled to dynamical Holstein phonons at integer and fractional fillings using density-matrix renormalization group with local basis optimization. We find that the low-energy effects of phonons are dominated by their dressing of charge-neutral collective modes. In the CI and FCI, phonons dress excitons and magnetorotons into composite modes that we identify as exciton polarons and magnetoroton polarons, respectively. These modes soften strongly upon approaching the transition, while the momenta of their energy minima anticipate the ordering wave vectors of the charge-ordered phases. The phonon spectrum, in turn, acquires dispersive features inherited from the exciton and magnetoroton modes, providing direct lattice signatures of these neutral excitations. Within the FCI phase, electron-phonon coupling also enhances the opposite-chirality spectral weight of the graviton response, thereby resulting in a chirality deficit. Our results provide a unified excitation-based picture of phonon-driven instabilities in CIs and FCIs and establish lattice dynamics as a probe of their neutral collective modes.
Comments4+22 pages, 4 + 18 figures
