论文标题
电场可调的非常规超导性魔术角三层石墨烯
Electric field tunable unconventional superconductivity in alternating twist magic-angle trilayer graphene
论文作者
论文摘要
我们构建了一个范德华异质结构，该异质结构由三个石墨烯层组成，这些石墨烯层和交替的扭转角$ \pmθ$。在平均扭曲角度$θ\ sim 1.56^{\ Circ} $上，理论上预测的魔术角，用于形成平面电子频段，窄传导和ValenceMoiré频段以及线性分散的Dirac频段一起出现。在用孔或带有电子的半填充的Moiré导带掺杂半填充的Moiré价带后，出现了位移场可调超导性，在最佳掺杂和位移场时达到2.1 K的最大临界温度。通过调整掺杂水平和位移场，我们发现超导状态与高位移磁场上的van霍夫奇异性（VHS）界定的Moiré波段的风味极化发生。发现该实验性观察与弱耦合描述不一致，这表明观察到的Moiré超导性具有非常规的性质。
We construct a van der Waals heterostructure consisting of three graphene layers stacked with alternating twisting angles $\pmθ$. At the average twist angle $θ\sim 1.56^{\circ}$, a theoretically predicted magic angle for the formation of flat electron bands, narrow conduction and valence moiré bands appear together with a linearly dispersing Dirac band. Upon doping the half-filled moiré valence band with holes, or the half-filled moiré conduction band with electrons, displacement field tunable superconductivity emerges, reaching a maximum critical temperature of 2.1 K at optimal doping and displacement field. By tuning the doping level and displacement fields, we find that superconducting regimes occur in conjunction with flavour polarization of moiré bands bounded by a van Hove singularity (vHS) at high displacement fields. This experimental observation is found to be inconsistent with a weak coupling description, suggesting that the observed moiré superconductivity has an unconventional nature.
