论文标题
扭曲双层石墨烯中瞬态2D钻石结构的超快形成
Ultrafast formation of transient 2D diamond-like structure in twisted bilayer graphene
论文作者
论文摘要
由于在相邻石墨烯片中没有碳原子的蜂窝中心没有匹配的碳原子，因此理论家预测，在将石墨直接转换为SP3键合的钻石时，需要滑动过程来形成AA，AB或ABC堆叠。在这里，使用自然提供AA和AB堆叠构型的扭曲双层石墨烯，我们报告了在飞秒激光辐照下的瞬态2D钻石状结构（在对齐的石墨烯中未观察到的）的超快形成。使用MEV Ultrafast Electron衍射在时间依赖性的差异分布函数中，新的键长的1.94a和3.14a的出现证明了这种照片诱导的相变。分子动力学和第一原理计算表明，SP3在Moire模式下在AA和AB堆叠的区域键合。这项工作阐明了直接的石墨到钻石转化机制，该机制已有60多年的历史了。
Due to the absence of matching carbon atoms at honeycomb centers with carbon atoms in adjacent graphene sheets, theorists predicted that a sliding process is needed to form AA, AB, or ABC stacking when directly converting graphite into sp3 bonded diamond. Here, using twisted bilayer graphene, which naturally provides AA and AB stacking configurations, we report the ultrafast formation of a transient 2D diamond-like structure (which is not observed in aligned graphene) under femtosecond laser irradiation. This photo-induced phase transition is evidenced by the appearance of new bond lengths of 1.94A and 3.14A in the time-dependent differential pair distribution function using MeV ultrafast electron diffraction. Molecular dynamics and first principles calculation indicate that sp3 bonds nucleate at AA and AB stacked areas in moire pattern. This work sheds light on the direct graphite-to-diamond transformation mechanism, which has not been fully understood for more than 60 years.
