论文标题
扭曲的三重双层石墨烯中的几乎平坦带
Nearly flat bands in twisted triple bilayer graphene
论文作者
论文摘要
We investigate the electronic structure of alternating-twist triple Bernal-stacked bilayer graphene (t3BG) as a function of interlayer coupling $ω$, twist angle $θ$, interlayer potential difference $Δ$, and top-bottom bilayers sliding vector $\boldsymbolτ$ for three possible configurations AB/AB/AB, AB/BA/AB, and AB/AB/BA.通过有限的层间电势差$δ$在Bernal堆叠的双层和间隙开放中的抛物线寄生虫低能带分散$Δ$可以使T3BG中的频段降低至$ \ sim 20 $ 〜MEV，以获取twist Angles $θ\ layssim 2^{\ circ} $ nestsim 2^{\ circ} $ nestect类型。由于双层石墨烯的固有间隙（用于有限的$δ$）的固有间隙，平面频带的隔离和相关的降低相关的降低，当将相关驱动的间隙与电场下扭曲的三层石墨烯的金属相比较时，有助于形成相关驱动的间隙。我们在$θ$和$δ$参数空间中获得了堆叠依赖的库仑能量与带宽$ u/w \ gtrsim 1 $比率。我们还提出了预期的$ k $ -Valley Chern数字，用于最低能量的几乎平坦的乐队。
We investigate the electronic structure of alternating-twist triple Bernal-stacked bilayer graphene (t3BG) as a function of interlayer coupling $ω$, twist angle $θ$, interlayer potential difference $Δ$, and top-bottom bilayers sliding vector $\boldsymbolτ$ for three possible configurations AB/AB/AB, AB/BA/AB, and AB/AB/BA. The parabolic low-energy band dispersions in a Bernal-stacked bilayer and gap-opening through a finite interlayer potential difference $Δ$ allows the flattening of bands in t3BG down to $\sim 20$~meV for twist angles $θ\lesssim 2^{\circ}$ regardless of the stacking types. The easier isolation of the flat bands and associated reduction of Coulomb screening thanks to the intrinsic gaps of bilayer graphene for finite $Δ$ facilitate the formation of correlation-driven gaps when it is compared to the metallic phases of twisted trilayer graphene under electric fields. We obtain the stacking dependent Coulomb energy versus bandwidth $U/W \gtrsim 1$ ratios in the $θ$ and $Δ$ parameter space. We also present the expected $K$-valley Chern numbers for the lowest-energy nearly flat bands.
