论文标题
扭曲的双层石墨烯中的弹道电荷运输
Ballistic charge transport in twisted bilayer graphene
论文作者
论文摘要
我们研究了在两个设置中偶联的扭曲的双层石墨烯之间的电导：在无限石墨烯色带上的一块石墨烯和两个重叠的半侵入石墨烯丝带。我们发现电导很大程度上取决于两个石墨烯层之间的角度，并确定了三个定性不同的方案。对于大角度（$θ\ gtrsim 10^{\ circ} $），对于不相关的角度具有强大的可相应性效应，低能电导接近两个断开的层的接近，而尖锐的电导性特征与与小单位细胞相关的相关性。对于中间角度（$ 3^{\ circ} \ Lesssimθ\ Lessim 10^{\ Circ} $），我们发现某些电导功能与扭曲依赖性的Van Hove奇异性之间的一对一对应关系在低能引起，表明可以使用用于确定扭转角度的电导率测量值。对于小扭曲角（$ 1^{\ circ} \Lessimθ\ Lessim 3^{\ circ} $），似乎将相应效果被洗净，并且电导变成了角度的平滑函数。在此制度中，电导可用于探测狭窄的频带，而消失的电导区域与状态密度的光谱间隙相对应，与最近的实验发现一致。
We study conductance across a twisted bilayer graphene coupled to single-layer graphene leads in two setups: a flake of graphene on top of an infinite graphene ribbon and two overlapping semi-infinite graphene ribbons. We find conductance strongly depends on the angle between the two graphene layers and identify three qualitatively different regimes. For large angles ($θ\gtrsim 10^{\circ}$) there are strong commensurability effects for incommensurate angles the low energy conductance approaches that of two disconnected layers, while sharp conductance features correlate with commensurate angles with small unit cells. For intermediate angles ($3^{\circ}\lesssim θ\lesssim 10^{\circ}$), we find a one-to-one correspondence between certain conductance features and the twist-dependent Van Hove singularities arising at low energies, suggesting conductance measurements can be used to determine the twist angle. For small twist angles ($1^{\circ}\lesssimθ\lesssim 3^{\circ}$), commensurate effects seem to be washed out and the conductance becomes a smooth function of the angle. In this regime, conductance can be used to probe the narrow bands, with vanishing conductance regions corresponding to spectral gaps in the density of states, in agreement with recent experimental findings.
