论文标题
最小扭曲的双层石墨烯的有效浮子模型
Effective Floquet model for minimally twisted bilayer graphene
论文作者
论文摘要
我们为三角网络构建了一个有效的浮子晶格模型，该模型出现在层间偏置的微型双层石墨烯中，并支持给定山谷和自旋的每个链接的两个手性通道。我们使用单渠道三角网络介绍了Floquet方案，然后将其扩展到两通道案例。从散装拓扑指数（绕组数）和有限系统计算中，我们发现两种情况都具有不同开放机制的异常浮光绝缘体（AFIS）。在单渠道网络中，必须打破时间反转或平面内反转对称性以打开差距。相比之下，在两通道网络中，频道耦合可以打开差距，而不会破坏这些对称性，从而产生了具有反向质边状态的山谷AFI。相对于总绕组数量，该阶段在拓扑上是微不足道的，但在没有间隔散射的情况下稳健。最后，我们通过磁转运计算证明了Floquet模型的适用性。
We construct an effective Floquet lattice model for the triangular network that emerges in interlayer-biased minimally twisted bilayer graphene and which supports two chiral channels per link for a given valley and spin. We introduce the Floquet scheme with the one-channel triangular network and subsequently extend it to the two-channel case. From the bulk topological index (winding number) and finite system calculations, we find that both cases host anomalous Floquet insulators (AFIs) with a different gap-opening mechanism. In the one-channel network, either time-reversal or in-plane inversion symmetry has to be broken to open a gap. In contrast, in the two-channel network, interchannel coupling can open a gap without breaking these symmetries yielding a valley AFI with counterpropagating edge states. This phase is topologically trivial with respect to the total winding number but robust in the absence of intervalley scattering. Finally, we demonstrate the applicability of the Floquet model with magnetotransport calculations.
