论文标题
魔法扭曲双层石墨烯中的电荷分布和旋转纹理
Charge distribution and spin textures in magic-angle twisted bilayer graphene
论文作者
论文摘要
我们将共存的自旋和电荷密度波作为魔法扭曲的双层石墨烯的可能基态。当不包括相互作用时，材料的光谱具有4个（如果考虑到旋转，则为8个）几乎是平坦的几乎变性带。相互作用分解形成顺序参数的退化，通常假定为具有预设旋转结构的旋转密度波。在这里，我们考虑了可能的电荷密度波对顺序参数的贡献，即在扭曲的石墨烯超细胞内电荷密度的不均匀分布。我们还可以自言自语地计算顺序参数的自旋结构。我们发现，密度波订单在整个掺杂范围内是稳定的，从$ -4 $到$+4 $ $ $ $ $。自旋质地从零掺杂的共线变为有限掺杂时几乎几乎是共面。当我们掺入系统时，密度波顺序显示出列的失真。我们证明，局部自旋磁化比电荷密度变化要强得多，除非掺杂量超过$ 3 $额外的电子或每个超级电池的孔。
We examine the coexisting spin and charge density waves as a possible ground state of the magic-angle twisted bilayer graphene. When interactions are not included, the spectrum of the material has 4 (8 if spin is taken into account) almost flat almost degenerate bands. Interactions break down the degeneracy forming an order parameter which is usually assumed to be a spin density wave with a preset spin structure. Here we take into account a possible charge density wave contribution to the order parameter, that is, inhomogeneous distribution of the charge density within a twisted graphene supercell. We also calculate self-consistently the spin structure of the order parameter. We find that the density wave order is stable in the whole doping range from $-4$ to $+4$ extra electrons per supercell. The spin texture changes from collinear at zero doping to almost coplanar at finite doping. The density wave order shows nematic distortion when we dope the system. We demonstrate that the local spin magnetization is much stronger than the charge density variation, unless the doping exceeds $3$ extra electrons or holes per supercell.
