Ultrasoft slip-mediated bending in few-layer graphene
Ultrasoft slip-mediated bending in few-layer graphene
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DOI：
10.1038/s41563-019-0529-7
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发表时间：
2020-03-01
期刊：
影响因子：
41.2
通讯作者：
van der Zande, Arend M.
中科院分区：
文献类型：
--
作者：
Han, Edmund;Yu, Jaehyung;van der Zande, Arend M.
当材料接近原子长度尺度时，连续尺度定律通常会失效，这反映了其底层物理特性的变化以及获得非常规特性的机会。这些连续体限制在二维材料中是明显的，在二维材料中，它们的弯曲刚度或它们如何随厚度缩放没有共识。通过计算和电子显微镜相结合的实验，我们测量了石墨烯的弯曲刚度，得到单层石墨烯的弯曲刚度为1.2-1.7 eV。此外，我们发现少层石墨烯的弯曲刚度随着弯曲角度的变化而急剧下降，三层石墨烯的弯曲刚度几乎下降了400%。这种软化是由于原子层之间的剪切、滑动和超润滑的开始，并且与标度从立方到线性的逐渐变化相对应。我们的研究结果为二维材料的弯曲提供了一个统一的模型，并表明它们的多层可以比以前认为的要软几个数量级，是目前已知的最灵活的电子材料之一。由于原子层之间的剪切和滑移，低层石墨烯的弯曲刚度随着弯曲角度的增加而显著降低，随着弯曲角度的进一步增加，这最终导致了超润滑行为。
Continuum scaling laws often break down when materials approach atomic length scales, reflecting changes in their underlying physics and the opportunities to access unconventional properties. These continuum limits are evident in two-dimensional materials, where there is no consensus on their bending stiffnesses or how they scale with thickness. Through combined computational and electron microscopy experiments, we measure the bending stiffness of graphene, obtaining 1.2-1.7 eV for a monolayer. Moreover, we find that the bending stiffness of few-layer graphene decreases sharply as a function of bending angle, tuning by almost 400% for trilayer graphene. This softening results from shear, slip and the onset of superlubricity between the atomic layers and corresponds with a gradual change in scaling power from cubic to linear. Our results provide a unified model for bending in two-dimensional materials and show that their multilayers can be orders of magnitude softer than previously thought, among the most flexible electronic materials currently known.The bending stiffness of few-layer graphene is shown to decrease significantly with the bending angle due to shear and slip between the atomic layers, which culminate in superlubric behaviour as the bending angle further increases.