论文标题
扭曲双层石墨烯的8-轨道模型中的相互作用
Interactions in the 8-orbital model for twisted bilayer graphene
论文作者
论文摘要
我们计算了扭曲双层石墨烯（TBG）的8-轨道模型的Wannier函数之间的相互作用。在此模型中，每个山谷以AA区域为中心的两个轨道，AA-P轨道，大部分是平底带的光谱重量。发现这些轨道之间的交换和辅助杂音术语很小。因此，TBG的低能特性将由密度密度相互作用确定。在没有门的情况下，这些相互作用与两个轨道模型的衰减速度要快得多。模型中最大相互作用的大小，即平面轨道之间的现场项，由AA区域的大小控制，估计约为40 meV。为了筛选这种相互作用，必须将金属门放在小于5 nm的距离处。对于较大的距离，仅筛选了相互作用的远距离部分。该模型再现了在哈特里近似中的其他方法中发现的掺杂引起的带变形。这种变形揭示了平坦带中其他轨道的存在，并且对涉及它们的相互作用的包含敏感。
We calculate the interactions between the Wannier functions of the 8-orbital model for twisted bilayer graphene (TBG). In this model, two orbitals per valley centered at the AA regions, the AA-p orbitals, account for the most part of the spectral weight of the flats bands. Exchange and assisted-hopping terms between these orbitals are found to be small. Therefore, the low energy properties of TBG will be determined by the density-density interactions. These interactions decay with the distance much faster than in the two orbital model, following a 1/r law in the absence of gates. The magnitude of the largest interaction in the model, the onsite term between the flat band orbitals, is controlled by the size of the AA regions and is estimated to be ~ 40 meV. To screen this interaction, the metallic gates have to be placed at a distance smaller than 5 nm. For larger distances only the long-range part of the interaction is substantially screened. The model reproduces the band deformation induced by doping found in other approaches within the Hartree approximation. Such deformation reveals the presence of other orbitals in the flat bands and is sensitive to the inclusion of the interactions involving them.
