论文标题
Chern-runsulator阶段以及自发的旋转和山谷秩序，用于魔术角式双层石墨烯的Moiré晶格模型
Chern-insulator phases and spontaneous spin and valley order in a moiré lattice model for magic-angle twisted bilayer graphene
论文作者
论文摘要
在两个石墨烯片的某个“魔术”相对扭曲角上，获得相关拓扑电子相位及其填充依赖性的详细描述的详细描述仍然是一个挑战。我们对有效的Moir {é}晶格模型进行了自洽的真实空间Hartree-fock研究，以绘制出首选有序相，作为库仑相互作用强度的函数和moir {é}平面填充因子。发现在所有整数填充物中都存在以前在电荷中立性发现的量子谷霍尔阶段，以实现足够大的相互作用。但是，除了电荷中立性外，在非零整数填充物处的基态存在其他自发旋转/山谷极化，从而导致Chern-umbulator阶段和异常的量子霍尔在奇数填充因子处效应，从而构成了相互作用驱动的非繁琐拓扑的示例。在较弱的相互作用下，所有非零整数填充物具有金属不均匀的自旋/山谷有序相位，这也可能破坏系统的其他点组对称性。我们根据以前的理论研究和魔法扭曲双层石墨烯的最新实验发展讨论这些发现。
At a certain "magic" relative twist angle of two graphene sheets it remains a challenge to obtain a detailed description of the proliferation of correlated topological electronic phases and their filling-dependence. We perform a self-consistent real-space Hartree-Fock study of an effective moir{é} lattice model to map out the preferred ordered phases as a function of Coulomb interaction strength and moir{é} flat-band filling factor. It is found that a quantum valley Hall phase, previously discovered at charge neutrality, is present at all integer fillings for sufficiently large interactions. However, except from charge neutrality additional spontaneous spin/valley polarization is present in the ground state at nonzero integer fillings, leading to Chern-insulator phases and anomalous quantum Hall effects at odd filling factors, thus constituting an example of interaction-driven nontrivial topology. At weaker interactions, all nonzero integer fillings feature metallic inhomogeneous spin/valley ordered phases which may also break additional point group symmetries of the system. We discuss these findings in the light of previous theoretical studies and recent experimental developments of magic-angle twisted bilayer graphene.
