Li Lijia, Chen Jiajun, Hu Laigui, Qiu Zhijun, Zou Zhuo, Liu Ran, Zheng Lirong, Cong Chunxiao
School of Information Science and Technology, Fudan University, Shanghai, PR China.
Yiwu Research Institute of Fudan University, Yiwu, Zhejiang, PR China.
Nat Commun. 2025 May 2;16(1):4117. doi: 10.1038/s41467-025-59325-w.
Collective vibration is pivotal for materials' thermal, electrical, phase transition and topological properties. Lately, the rising of moiré superlattices, characterized by overarching periodicity of moiré pattern, generates highly tunable interfacial structures that manipulate collective excitations in material at the atomic scale. Here, we experimentally demonstrate moiré collective vibrations, the mechanical counterparts of moiré excitons, at heterointerfaces of twisted tungsten diselenide/tungsten disulfide heterobilayers. Using helicity-resolved inelastic Raman scattering, we find chiral interfacial phonons carrying angular momentum analogous to that of chiral bulk phonons in quartz, enabling unprecedented spectral resolution of rich vibrational modes at heterointerface in a few atomic layers. Upon mutual torsion of heterobilayers, we observe terahertz interlayer vibrations proportional to moiré periodicity as a periodic function of rotation angles, demonstrating moiré-tuned interlayer modes which couple to Coulomb-bound electron-hole pairs in interlayer moiré excitons. In low-angle strong coupling regime, interlayer dynamics exhibit a distinct long-lived breathing mode with zero angular momentum and pronounced high energy, highlighting phonon-hybridization character wherein intralayer breathing vibrations are folded into moiré mini-Brillouin zone by spatial periodicity and hybridize with interlayer vibrations. Our findings establish moiré collective vibrations as candidates for exploitation in energy-efficient thermal management, strongly correlated electrical engineering, and new emergent topological phononics.
集体振动对于材料的热、电、相变和拓扑性质至关重要。最近，以莫尔条纹的总体周期性为特征的莫尔超晶格的兴起，产生了高度可调谐的界面结构，能够在原子尺度上操纵材料中的集体激发。在这里，我们通过实验证明了扭曲的二硒化钨/二硫化钨异质双层的异质界面处存在莫尔集体振动，即莫尔激子的力学对应物。利用螺旋度分辨非弹性拉曼散射，我们发现手性界面声子携带的角动量与石英中的手性体声子类似，这使得在几个原子层的异质界面处能够以前所未有的光谱分辨率分辨丰富的振动模式。在异质双层相互扭转时，我们观察到太赫兹层间振动与莫尔周期成正比，是旋转角度的周期函数，这表明了莫尔调谐的层间模式，该模式与层间莫尔激子中库仑束缚的电子-空穴对耦合。在小角度强耦合 regime 中，层间动力学表现出一种独特的长寿命呼吸模式，其角动量为零且能量明显较高，突出了声子杂交的特征，即层内呼吸振动通过空间周期性折叠到莫尔小布里渊区并与层间振动杂交。我们的发现确立了莫尔集体振动作为在节能热管理、强关联电气工程和新出现的拓扑声子学中开发利用的候选对象。
