Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC), Cantoblanco, 28049 Madrid, Spain.
Nano Lett. 2014;14(4):2052-7. doi: 10.1021/nl500230a. Epub 2014 Mar 12.
Pristine bilayer graphene behaves in some instances as an insulator with a transport gap of a few millielectronvolts. This behavior has been interpreted as the result of an intrinsic electronic instability induced by many-body correlations. Intriguingly, however, some samples of similar mobility exhibit good metallic properties with a minimal conductivity of the order of 2e(2)/h. Here, we propose an explanation for this dichotomy, which is unrelated to electron interactions and based instead on the reversible formation of boundaries between stacking domains ("solitons"). We argue, using a numerical analysis, that the hallmark features of the previously inferred many-body insulating state can be explained by scattering on boundaries between domains with different stacking order (AB and BA). We furthermore present experimental evidence, reinforcing our interpretation, of reversible switching between a metallic and an insulating regime in suspended bilayers when subjected to thermal cycling or high current annealing.
原始的双层石墨烯在某些情况下表现为具有几毫电子伏特传输间隙的绝缘体。这种行为被解释为多体相关性引起的固有电子不稳定性的结果。然而，有趣的是，一些具有类似迁移率的样品表现出良好的金属性质，其最小电导率约为 2e(2)/h。在这里，我们提出了一种解释这种二分法的方法，这种方法与电子相互作用无关，而是基于堆叠畴之间的边界（“孤子”）的可逆形成。我们使用数值分析来论证，先前推断出的多体绝缘状态的显著特征可以通过在具有不同堆叠顺序（AB 和 BA）的畴之间的边界上的散射来解释。此外，我们还提出了实验证据，当悬浮双层石墨烯经受热循环或高电流退火时，在金属和绝缘状态之间的可逆切换，增强了我们的解释。
