Zhang Xin, Makles Kevin, Colombier Léo, Metten Dominik, Majjad Hicham, Verlot Pierre, Berciaud Stéphane
Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, F-67000, Strasbourg, France.
School of Physics and Astronomy, University of Nottingham, Nottingham, NG7 2RD, United Kingdom.
Nat Commun. 2020 Nov 2;11(1):5526. doi: 10.1038/s41467-020-19261-3.
Graphene and related two-dimensional (2D) materials associate remarkable mechanical, electronic, optical and phononic properties. As such, 2D materials are promising for hybrid systems that couple their elementary excitations (excitons, phonons) to their macroscopic mechanical modes. These built-in systems may yield enhanced strain-mediated coupling compared to bulkier architectures, e.g., comprising a single quantum emitter coupled to a nano-mechanical resonator. Here, using micro-Raman spectroscopy on pristine monolayer graphene drums, we demonstrate that the macroscopic flexural vibrations of graphene induce dynamical optical phonon softening. This softening is an unambiguous fingerprint of dynamically-induced tensile strain that reaches values up to ≈4 × 10 under strong non-linear driving. Such non-linearly enhanced strain exceeds the values predicted for harmonic vibrations with the same root mean square (RMS) amplitude by more than one order of magnitude. Our work holds promise for dynamical strain engineering and dynamical strain-mediated control of light-matter interactions in 2D materials and related heterostructures.
石墨烯及相关二维（2D）材料具有卓越的机械、电子、光学和声学特性。因此，二维材料对于将其基本激发（激子、声子）与宏观机械模式耦合的混合系统而言很有前景。与更庞大的结构相比，这些内置系统可能会产生增强的应变介导耦合，例如，由单个量子发射器耦合到纳米机械谐振器组成的结构。在这里，通过对原始单层石墨烯鼓进行显微拉曼光谱分析，我们证明了石墨烯的宏观弯曲振动会导致动态光学声子软化。这种软化是动态诱导拉伸应变的明确指纹，在强非线性驱动下，该应变值可达≈4×10 。这种非线性增强的应变比具有相同均方根（RMS）振幅的简谐振动预测值高出一个多数量级。我们的工作为二维材料及相关异质结构中的动态应变工程和动态应变介导的光与物质相互作用控制带来了希望。
