Chirality-Induced Phonon Dispersion in a Noncentrosymmetric Micropolar Crystal
Chirality-Induced Phonon Dispersion in a Noncentrosymmetric Micropolar Crystal
复制标题
DOI：
10.1103/physrevlett.125.245302
复制
发表时间：
2020-12-09
影响因子：
8.6
通讯作者：
Tereshchenko, A. A.
中科院分区：
文献类型：
--
作者：
Kishine, J.;Ovchinnikov, A. S.;Tereshchenko, A. A.
本文用微极弹性理论研究了手征晶体的声子谱特征。这种形式主义不仅解释了介质的平移微动，而且还解释了旋转微动。结果表明，在不引入任何外部子系统的情况下，在一个纯声子扇区中，存在依赖于左右圆极化的声子带分裂。声子谱揭示了宇称破缺，同时保持时间反演对称性，即，它具有真正的手性。我们发现微转动模和平移模的杂交产生了带有“转子”的声学声子分支。”最小值让人联想到超流氦-4中的基元激发。我们认为，这种现象的机制是符合Nozieres的重新解释P. Nozieres，[J.低温。137，45（2004）]中所述的结晶不稳定性。我们讨论了一个密切的类比之间的平移和旋转的微动在微极弹性介质和Bogoliubov准粒子和间隙密度波动的He-4。
Features of the phonon spectrum of a chiral crystal are examined within the micropolar elasticity theory. This formalism accounts for not only translational micromotions of a medium but also rotational ones. It is found that there appears the phonon band splitting depending on the left- and right-circular polarization in a purely phonon sector without invoking any outside subsystem. The phonon spectrum reveals parity breaking while preserving time-reversal symmetry, i.e., it possesses true chirality. We find that hybridization of the microrotational and translational modes gives rise to the acoustic phonon branch with a "rotor . '" minimum reminiscent of the elementary excitations in the superfluid helium-4. We argue that a mechanism of this phenomena is in line with Nozieres' reinterpretation P. Nozieres, [J. Low Temp. Phys. 137, 45 (2004)] of the rotons as a manifestation of an incipient crystallization instability. We discuss a close analogy between the translational and rotational micromotions in the micropolar elastic medium and the Bogoliubov quasiparticles and gapful density fluctuations in He-4.