Crystalline semiconductors with intrinsically low lattice thermal conductivity ($\mathcal{K}$) are vital for device applications such as barrier coatings and thermoelectrics. Quaternary chalcogenide semiconductors such as CuCd$_2$InTe$_4$ and CuZn$_2$InTe$_4$ are experimentally shown to exhibit low $\mathcal{K}$, yet its microscopic origin remains poorly understood. Here, we analyse their thermal transport mechanisms using a unified first-principles framework that captures both the Peierls (particle-like propagation, $\mathcal{K}_P$) and coherence (wave-like tunneling, $\mathcal{K}_C$) mechanisms of phonon transport. We show that extended antibonding states below the Fermi level lead to enhanced phonon anharmonicity and strong scattering of heat-carrying phonon modes, suppressing $\mathcal{K}$ in these chalcogenides. We show that $\mathcal{K}_P$ dominates the total thermal conductivity, while $\mathcal{K}_C$ remains negligible even under strong anharmonicity of the phonon modes. The heavier Cd ions in CuCd$_2$InTe$_4$ induce greater acoustic-optical phonon overlap and scattering compared to CuZn$_2$InTe$_4$, further lowering thermal conductivity of the former. Additionally, grain boundary scattering in realistic samples contributes to further suppression of thermal transport. Our findings establish the atomistic origins of low $\mathcal{K}$ in quaternary chalcogenides and offer guiding principles for designing low-thermal-conductivity semiconductors.
Structural stability, electronic band structure, and optoelectronic properties of quaternary chalcogenide CuZn2MS4 (M =In and Ga) compounds via first principles
All-optical detection of periodic structure of chalcogenide superlattice using coherent folded acoustic phonons
硫系超晶格（SL）由GeTe和Sb $_{2}$ Te $_{3}$层的交替堆叠组成。该结构可以根据组成层的厚度变成3D拓扑绝缘体，使得SL周期的设计成为推进硫属化物SL作为自旋器件的潜在候选以及优化当前一代相变存储器器件的中心问题。在这里，我们探索的周期性结构的硫属化物SL观察相干折叠纵向声学（FLA）声子激发飞秒激光脉冲照射。FLA模式的峰值频率被观察到的GeTe层的厚度，这是很好地再现通过一个弹性连续模型的变化时的变化。此外，一个新的SL结构的样品组成的薄GeTe和Sb $_{2}$ Te $_{3}$层，这表明混合的Ge原子。这种基于相干FLA模式观察的全光学技术提供了原子分辨率的超晶格结构的非破坏性表征。
