论文标题
扭曲双层石墨烯中的等离子狄拉克锥
Plasmonic Dirac Cone in Twisted Bilayer Graphene
论文作者
论文摘要
当费米水平位于间隙内部时，我们讨论了有偏的扭曲双层石墨烯的等离子体。集体激发是一个完全由AB-BA接口处的拓扑电子边缘状态（EES）组成的手性边缘等离子体（CEP）网络。 CEP形成一个具有独特能量比例的六边形网络$ε_p= \ frac {e^2} {ε_0εt_0} $，带有$ t_0 $ t_0 $ theMoirélattice常数和$ε$介质常数。从介电矩阵中，我们获得具有两个主要特征的等离子光谱：（i）零能量处的状态密度有分化的密度，以及（ii）在$ \hbarΩ\hbarΩ\simε_p/2 $中存在等离子dirac锥，并以声音$ v_d = 0.0075c $，由Zig和Armchair形成了Zig和Armchair和Armchair al Chig和Armchair，这是由声速$ v_d $ v_d = 0.0075c $。一个网络模型表明，等离子体带的反对称性意味着CEP在偏移的手性传出方向上最大程度地散布在六角形的顶点上，每个偏转方向的电流比为4/9，向前散射1/9。我们表明，扫描近场显微镜应该能够观察到预测的等离子狄拉克锥及其断裂的对称阶段。
We discuss plasmons of biased twisted bilayer graphene when the Fermi level lies inside the gap. The collective excitations are a network of chiral edge plasmons (CEP) entirely composed of excitations in the topological electronic edge states (EES) that appear at the AB-BA interfaces. The CEP form an hexagonal network with an unique energy scale $ε_p=\frac{e^2}{ε_0εt_0}$ with $t_0$ the moiré lattice constant and $ε$ the dielectric constant. From the dielectric matrix we obtain the plasmon spectra that has two main characteristics: (i) a diverging density of states at zero energy, and (ii) the presence of a plasmonic Dirac cone at $\hbarω\simε_p/2$ with sound velocity $v_D=0.0075c$, which is formed by zigzag and armchair current oscillations. A network model reveals that the antisymmetry of the plasmon bands implies that CEP scatter at the hexagon vertices maximally in the deflected chiral outgoing directions, with a current ratio of 4/9 into each of the deflected directions and 1/9 into the forward one. We show that scanning near-field microscopy should be able to observe the predicted plasmonic Dirac cone and its broken symmetry phases.
