Electric field-tunable superconductivity in alternating-twist magic-angle trilayer graphene
Electric field-tunable superconductivity in alternating-twist magic-angle trilayer graphene
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DOI：
10.1126/science.abg0399
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发表时间：
2021-03-12
期刊：
影响因子：
56.9
通讯作者：
Kim, Philip
中科院分区：
文献类型：
--
作者：
Hao, Zeyu;Zimmerman, A. M.;Kim, Philip
利用范德华（vdW）异质结构中的扭转层来设计云纹超晶格已经揭示了一系列广泛的量子现象。我们构建了一个vdW异质结构，它由三个石墨烯层组成，以交替的扭曲角度+/-堆叠。在平均扭转角为1.56度的情况下，我们观察到最大临界温度为2.1开尔文的位移场可调谐超导性。通过调整掺杂水平和位移场，我们发现超导状态与云纹带的风味极化同时发生，并且在高位移场中被van Hove奇点（vHS）所包围。我们的发现与弱耦合描述不一致，表明观察到的云纹超导性具有非常规的性质。
Engineering moire superlattices by twisting layers in van der Waals (vdW) heterostructures has uncovered a wide array of quantum phenomena. We constructed a vdW heterostructure that consists of three graphene layers stacked with alternating twist angles +/- theta. At the average twist angle theta similar to 1.56 degrees, a theoretically predicted "magic angle" for the formation of flat electron bands, we observed displacement field-tunable superconductivity with a maximum critical temperature of 2.1 kelvin. By tuning the doping level and displacement field, we found that superconducting regimes occur in conjunction with flavor polarization of moire bands and are bounded by a van Hove singularity (vHS) at high displacement fields. Our findings display inconsistencies with a weak coupling description, suggesting that the observed moire superconductivity has an unconventional nature.