论文标题
魔法扭曲的双层石墨烯在六角硼硼级上的不稳定不稳定
Misalignment instability in magic-angle twisted bilayer graphene on hexagonal boron nitride
论文作者
论文摘要
我们研究了硝化硼（TBG/bn）上魔法扭曲的双层石墨烯的稳定性和电子结构。对于具有不同扭曲角度（$θ'$）的异质结构的相应超级电池和TBG和BN之间的堆叠，已经进行了完全的放松。我们发现，由于Moiré中间层潜能的建设性干扰，因此具有$θ'= 0.54^\ Circ $的略微不一致的配置，AA/AA堆叠具有全球最低的总能量，因此在其$ 1 \ Times 1 $ 1 $ Commentrate Supercell中大大增强了放松。对于小型超级细胞，在费米级别（$ e_f $）开设了差距，其堆叠量可以在TBG原子结构中强烈破坏$ C_2 $对称性。对于$θ'$的大型超级电池，靠近$ 1 \ times 1 $超级电池的大型超级单车，仍然可以从频谱函数中解决宽阔的平坦频段。 $θ'= 0.54^\ circ $也被确定为具有$θ'$的电子结构演变的关键角度，在$ e_f $ $ e_f $左右的迷你频段的能量范围开始变得狭窄，随着$θ'$的增加，它们的差距从分散频段开始变得更宽。发现的最稳定的TBG/BN，有限的$θ'$约为$ 0.54^\ circ $，其间隙的平坦乐队与最近的实验观察一致。
We study the stability and electronic structure of magic-angle twisted bilayer graphene on the hexagonal boron nitride (TBG/BN). Full relaxation has been performed for commensurate supercells of the heterostructures with different twist angles ($θ'$) and stackings between TBG and BN. We find that the slightly misaligned configuration with $θ' = 0.54^\circ$ and the AA/AA stacking has the globally lowest total energy due to the constructive interference of the moiré interlayer potentials and thus the greatly enhanced relaxation in its $1 \times 1$ commensurate supercell. Gaps are opened at the Fermi level ($E_F$) for small supercells with the stackings that enable strong breaking of the $C_2$ symmetry in the atomic structure of TBG. For large supercells with $θ'$ close to those of the $1 \times 1$ supercells, the broadened flat bands can still be resolved from the spectral functions. The $θ' = 0.54^\circ$ is also identified as a critical angle for the evolution of the electronic structure with $θ'$, at which the energy range of the mini-bands around $E_F$ begins to become narrower with increasing $θ'$ and their gaps from the dispersive bands become wider. The discovered stablest TBG/BN with a finite $θ'$ of about $0.54^\circ$ and its gapped flat bands agree with recent experimental observations.
