过渡金属二硫属化物中的手性电荷密度波
Chiral charge density waves in transition metal dichalcogenide
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中文总结 AI 辅助
研究1$T$-TiSe$_2$中电荷密度波相手性微观起源，通过密度泛函理论和对称性分析，发现近简并亚稳CDW相堆积顺序，其具有双重物理性质，确定局部探针中“自发”手性是相堆积域统计分布，建立光致旋光序机制。
中文摘要 AI 辅助
1$T$-TiSe$_2$电荷密度波（CDW）相中手性的出现最近备受关注，但其微观起源仍有争议。主流观点将手性归因于电荷密度分量之间的相对相移。本文通过密度泛函理论和对称性分析表明，这种相移态存在高昂能量成本，不太可能是基态候选。相反，确定了一种具有单斜对称性的近简并亚稳CDW相堆积顺序，它自然打破了镜面对称和反演对称。1$T$-TiSe$_2$中的CDW具有双重物理性质，电子电荷重新分布本质上由键调制，周期性晶格畸变是以原子为中心的横向畸变。这种空间分离允许一种特定的光学耦合机制，圆偏振光打破手性域之间的能量简并。这些结果调和了相互矛盾的实验观察，确定了在局部探针中观察到的“自发”手性是CDW相堆积域的统计分布，同时建立了宏观光致旋光序的机制。
英文摘要
The emergence of chirality in the charge density wave (CDW) phase of 1$T$-TiSe$_2$ has recently attracted significant attention, yet its microscopic origin remains debated. The prevailing interpretation attributes chirality to a relative phase shift between the charge density components. Here, using density functional theory and symmetry analysis, it is demonstrated that such phase-shifted states entail prohibitive energy costs, rendering them unlikely candidates for the ground state. Instead, a nearly degenerate metastable CDW phase stacking order with monoclinic symmetry is identified, that naturally breaks mirror and inversion symmetries. The CDW in 1$T$-TiSe$_2$ possesses a dual physical nature: the electronic charge redistribution is intrinsically bond-modulated, while the periodic lattice distortion is atom-centered transverse. This spatial separation allows a specific optical coupling mechanism where circularly polarized light breaks the energetic degeneracy between chiral domains. These results reconcile conflicting experimental observations, identifying the "spontaneous" chirality observed in local probes as a statistical distribution of CDW phase stacking domains, while establishing the mechanism for macroscopic, light-induced gyrotropic order.
