论文标题
薄片中不寻常的照片声波的纳米级成像VTE $ _2 $
Nanoscale imaging of unusual photo-acoustic waves in thin flake VTe$_2$
论文作者
论文摘要
声音和热的载体控制声音，一直在引起人们对纳米设备中声音和热性能的操纵的极大关注。特别是，使用超快光脉冲的光声效应具有在Picseconds时间状态下光学操纵声子的有希望的潜力。但是，到目前为止，其机制主要基于各向同性介质中普通的热弹性扩展，从而限制了潜在应用的范围。我们通过利用带状型电荷密度 - 波（CDW），利用过渡金属二核苷vte $ _2 $（CDW）研究了涉及结构不稳定性的光声效应的新机制。超快电子显微镜成像和衍射测量结果揭示了与光学诱导的瞬时电荷密度波溶解相关的纳米薄板中异常声波的产生和传播。我们的结果突出了光诱导的结构不稳定性作为相干声波的来源的能力。
Controlling acoustic phonons, the carriers of sound and heat, has been attracting great attention toward the manipulation of sonic and thermal properties in nanometric devices. In particular, the photo-acoustic effect using ultrafast optical pulses has a promising potential to optically manipulate phonons in picoseconds time regime. However, its mechanism has been so far mostly based on the commonplace thermoelastic expansion in isotropic media, limiting the spectrum of potential applications. We investigate a conceptually new mechanism of photo-acoustic effect involving the structural instability, by utilizing a transition-metal dichalcogenide VTe$_2$ with the ribbon-type charge-density-wave (CDW). Ultrafast electron microscope imaging and diffraction measurements reveal the generation and propagation of unusual acoustic waves in the nanometric thin plate associated with the optically induced instantaneous charge-density-wave dissolution. Our results highlight the capability of photo-induced structural instability as a source of coherent acoustic waves.
