AI 中文总结
该研究通过拉曼散射测量和理论计算，证实K3NiO2在约400K发生非手性到手性四方相的结构相变，由Z点软声子诱导，还发现其手性相存在具角动量的拓扑声子。
AI 中文摘要
拉曼散射测量证实了理论预测：在约400K附近发生的从非手性四方相到手性四方相的结构相变，由布里渊区Z点处的二重简并软声子诱导。在低温手性相中，软模在拉曼光谱中被激活，分裂为具有A1和B1对称性的两个分量，并根据科克伦定律随温度降低而硬化。圆偏振拉曼散射未揭示这些Γ点处单重简并声子的角动量，这与理论一致。我们还计算了两个晶相在整个布里渊区的声子支，并将结果与拉曼光谱中可观测的声子进行了比较。计算显示，手性相中部分非零波矢k的声子具有角动量，例如布里渊区M点处频率为168cm-1的狄拉克型拓扑声子中可观测到明显的原子圆周运动。
英文摘要
Raman scattering measurements confirmed the theoretical prediction that the structural phase transition from the achiral tetragonal to the chiral tetragonal phase, which occurs near 400 K, is induced by a doubly degenerate soft phonon at the Z point of the Brillouin zone. In the low-temperature chiral phase, the soft mode activates in Raman spectra, splits into two components with A1 and B1 symmetries and harden with cooling according to Cochran law. Circularly polarized Raman scattering did not reveal the angular momentum of these singly degenerate phonons at the Gamma point, which is consistent with theory. We also calculated the phonon branches in the whole Brillouin zone for both crystalline phases and compared the results with the phonons observable in the Raman spectra. The calculations revealed that some phonons with nonzero k have angular momentum in the chiral phase. A pronounced circular motion of atoms can be observed, for example, in a Dirac-type topological phonon at the M-point of the Brillouin zone with a frequency of 168 cm-1.
Comments17 pages, 8 figures
