论文标题
镜子对称分解在双吐线多层石墨烯系统中
Mirror symmetry decomposition in double-twisted multilayer graphene systems
论文作者
论文摘要
由于观察到的超导性，交替的扭曲三层石墨烯（ATTLG）最近引起了极大的研究兴趣，其中三个单层石墨烯（MLG）以交替的扭曲方式堆叠。如果ATTLG中的一个或几个MLG被多层石墨烯取代，我们将获得双扭曲的多层石墨烯（DTMLG）。在这项工作中，我们从理论上说明，如果DTMLG像ATTLG一样沿z方向具有镜像对称性，则存在镜像对称分解（MSD），可以将DTMLG精确地将其分解为具有相反平等的两个子系统。这两个子系统是扭曲的多层石墨烯（单个扭曲）或多层石墨烯，具体取决于堆叠配置。这样的MSD可以清楚地解释DTMLG的Moiré带结构的所有新颖特征，例如四倍的退化平坦带和扩大的魔法角度。同时，在这样的DTMLG中，均等成为电子的新自由度，因此我们可以为Moiré平面频段定义平价解决的Chern号码。更重要的是，MSD意味着扭曲的多层石墨烯中的所有新型相关阶段也应在相应的DTMLG中存在，因为它们的形式具有完全相同的Hamiltonian。具体而言，根据MSD，我们预测（1+3+1）-DTMLG中应该存在超导性。
Due to the observed superconductivity, the alternating twisted trilayer graphene (ATTLG) has drawn great research interest very recently, in which three monolayer graphene (MLG) are stacked in alternating twist way. If one or several of the MLG in ATTLG are replaced by a multilayer graphene, we get a double twisted multilayer graphene (DTMLG). In this work, we theoretically illustrate that, if the DTMLG has a mirror symmetry along z direction like the ATTLG, there exists a mirror symmetry decomposition (MSD), by which the DTMLG can be exactly decoupled into two subsystems with opposite parity. The two subsystems are either a twisted multilayer graphene (single twist) or a multilayer graphene, depending on the stacking configuration. Such MSD can give a clear interpretation about all the novel features of the moiré band structures of DTMLG, e.g. the fourfold degenerate flat bands and the enlarged magic angle. Meanwhile, in such DTMLG, the parity becomes a new degree of freedom of the electrons, so that we can define a parity resolved Chern number for the moiré flat bands. More importantly, the MSD implies that all the novel correlated phases in the twisted multilayer graphene should also exist in the corresponding DTMLGs, since they have the exact same Hamiltonian in form. Specifically, according to the MSD, we predict that the superconductivity should exist in the (1+3+1)-DTMLG.
