论文标题
扭曲的双层石墨烯中的时间逆转与手性对称性破裂
Time-reversal versus chiral symmetry breaking in twisted bilayer graphene
论文作者
论文摘要
通过应用自一致的Hartree-fock近似，我们表明动态对称性破裂的机理可以解释围绕魔术角绕扭曲的双层石墨烯的电荷中性点发展的绝缘阶段。 （$ i $）如果库仑的相互作用是通过金属门筛选的，则通过强耦合时的手性对称性击穿，可以通过最低能量价和传导带之间的差距开放。但是，增加了介电筛选，我们发现了抑制手性对称性破裂的临界耦合，从而触发了非常强的信号，以使时间反转对称性与Haldane质量破裂。 （$ ii $）如果未筛选库仑相互作用的远距离尾巴，我们会看到在强耦合时出现不同的主要图案，其特征是破坏了时间转换的不变性，但在每个碳层的两个sublattices中具有相反的磁通，并带有随之而来的谷谷对称性破坏。在这种情况下，狄拉克锥体也有一个差距，但在MoiréBrillouinZone的$ K $点上划分了低功能乐队的堕落。
By applying a self-consistent Hartree-Fock approximation, we show that the mechanism of dynamical symmetry breaking can account for the insulating phase that develops about the charge neutrality point of twisted bilayer graphene around the magic angle. ($i$) If the Coulomb interaction is screened by metallic gates, the opening of a gap between the lowest-energy valence and conduction bands proceeds through the breakdown of chiral symmetry at strong coupling. Increasing the dielectric screening, however, we find a critical coupling at which chiral symmetry breaking is suppressed, triggering a very strong signal for time-reversal symmetry breaking with Haldane mass. ($ii$) If the long-range tail of the Coulomb interaction is not screened, we see the appearance of yet a different dominant pattern at strong coupling, which is characterized by breaking the time-reversal invariance but with opposite flux in the two sublattices of each carbon layer, with the consequent valley symmetry breaking. In this case a gap is also opened in the Dirac cones, but superposed to the splitting of the degeneracy of the low-energy bands at the $K$ points of the moiré Brillouin zone.
