Rotational stability of twisted bilayer graphene
Rotational stability of twisted bilayer graphene
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DOI：
10.1103/physrevb.101.054109
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发表时间：
2020-02-25
影响因子：
3.7
通讯作者：
Chew, H. B.
中科院分区：
文献类型：
--
作者：
Bagchi, S.;Johnson, H. T.;Chew, H. B.
由于周期性的可折叠区域，在扭曲的石墨烯双层中形成莫尔超晶格，但是莫尔图案的截断影响有限尺寸片材的旋转稳定性。在这里，我们报告了纳米尺寸的双层石墨烯片在高温下的逐步解扭，每一步对应于由莫尔超晶格和片尺寸与扭转角之间的可伸缩性的变化形成的势能势垒。局部稳定能态的数量和它们的势垒能与薄片尺寸成比例，使得几十纳米的扭曲石墨烯薄片即使在化学气相沉积温度下也保持热稳定。
Moire superlattices form in twisted graphene bilayers due to periodic regions of commensurability, but truncation of the moire patterns affects the rotational stability of finite-sized sheets. Here, we report the stepwise untwisting of nanometer-sized bilayer graphene flakes at elevated temperatures, each step corresponding to a potential energy barrier formed by changes to the commensurability between the moire superlattice and flake size with twist angle. The number of locally stable energy states and their barrier energies scale with the flake size, allowing twisted graphene flakes of several tens of nanometers to remain thermally stable even at chemical vapor deposition temperatures.