论文标题
Moiré绝缘子的扁平带和手性光学响应
Flat bands and chiral optical response of moiré insulators
论文作者
论文摘要
我们提出了一个低能模型，描述了具有断裂的sublattice对称性的蜂窝晶体的扭曲双层中电子光谱的重建。所得的莫伊尔模式分为两个具有不同对称性的家庭。在这两种情况下，平面带出现在相对较大的角度，没有任何魔法角度条件。它们之间的过渡会在光吸收光谱中引起急剧的共振，频率远低于单层的间隙。由于它们的手性对称性，扭曲的双层显示圆形二色性，即左右圆形光的不同吸收。这种光学活性是由堆叠确定的非局部特性。在六角硼硝化物中，对堆叠的敏感性导致两种类型的莫伊尔人在圆形二色性方面截然不同。我们的计算说明了在层之间的电流相关中编码的电子波函数的微妙特性如何控制Moiré材料的物理可观察物。
We present a low-energy model describing the reconstruction of the electronic spectrum in twisted bilayers of honeycomb crystals with broken sublattice symmetry. The resulting moiré patterns are classified into two families with different symmetry. In both cases, flat bands appear at relatively large angles, without any magic angle condition. Transitions between them give rise to sharp resonances in the optical absorption spectrum at frequencies well below the gap of the monolayer. Owing to their chiral symmetry, twisted bilayers display circular dichroism, i.e., different absorption of left and right circularly-polarized light. This optical activity is a nonlocal property determined by the stacking. In hexagonal boron nitride, sensitivity to the stacking leads to strikingly different circular dichroism in the two types of moirés. Our calculations exemplify how subtle properties of the electronic wavefunctions encoded in current correlations between the layers control physical observables of moiré materials.
