Promotion of superconductivity in magic-angle graphene multilayers
Promotion of superconductivity in magic-angle graphene multilayers
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DOI：
10.1126/science.abn8585
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发表时间：
2022-09
期刊：
影响因子：
56.9
通讯作者：
Yiran Zhang;R. Polski;C. Lewandowski;A. Thomson;Yang Peng;Youngjoon Choi;Hyunjin Kim;Kenji Watanabe;T. Taniguchi;J. Alicea;F. von Oppen;G. Refael;S. Nadj-Perge
中科院分区：
文献类型：
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作者：
Yiran Zhang;R. Polski;C. Lewandowski;A. Thomson;Yang Peng;Youngjoon Choi;Hyunjin Kim;Kenji Watanabe;T. Taniguchi;J. Alicea;F. von Oppen;G. Refael;S. Nadj-Perge
石墨烯莫尔超晶格显示出丰富的相关绝缘，拓扑和超导相。虽然强关联和非平凡拓扑的起源可以直接与平带联系起来，但超导性的本质仍然是个谜。我们证明了魔角装置的扭曲的三，四，五层石墨烯放置在单层钨二硒化物表现出风味极化和超导性。我们还观察到绝缘状态的三层和四层在有限的电位移场。随着层数的增加，超导电性出现在一个增强的填充因子范围内，在五层中，它远远超出了每个莫尔晶胞填充四个电子的范围。我们的研究结果突出了平坦和更分散的带之间的相互作用在石墨烯莫尔超晶格中扩展超导区域的作用。描述极好的石墨烯多层膜石墨烯双层和三层由单层扭曲成直角组成，已被证明是超导的。为了获得对这些莫尔超晶格中的超导性的统一理解，希望增加已知的石墨烯莫尔超导体的数量。Zhang等人制造了由三层、四层和五层石墨烯层组成的样品，这些石墨烯层以交替的顺序相互扭曲。将这些石墨烯多层膜耦合到下面的二硒化钨单层。研究人员在所有三种类型的样品中都观察到了强大的超导性，随着层数的增加，相图的超导部分变得更加突出。-JS传输测量表明扭曲的三层，四层和五层石墨烯中的超导性。
Graphene moiré superlattices show an abundance of correlated insulating, topological, and superconducting phases. Whereas the origins of strong correlations and nontrivial topology can be directly linked to flat bands, the nature of superconductivity remains enigmatic. We demonstrate that magic-angle devices made of twisted tri-, quadri-, and pentalayer graphene placed on monolayer tungsten diselenide exhibit flavor polarization and superconductivity. We also observe insulating states in the tril- and quadrilayer arising at finite electric displacement fields. As the number of layers increases, superconductivity emerges over an enhanced filling-factor range, and in the pentalayer it extends well beyond the filling of four electrons per moiré unit cell. Our results highlight the role of the interplay between flat and more dispersive bands in extending superconducting regions in graphene moiré superlattices. Description Superb graphene multilayers Graphene bilayers and trilayers consisting of monolayers twisted at just the right angle have been shown to be superconducting. To acquire a unified understanding of superconductivity in these moiré superlattices, it is desirable to increase the number of known graphene moiré superconductors. Zhang et al. fabricated samples consisting of three, four, and five graphene layers that were twisted with respect to each other in an alternating sequence. These graphene multilayers were coupled to an underlying monolayer of tungsten diselenide. The researchers observed robust superconductivity in all three types of samples, with the superconducting portion of the phase diagram becoming more prominent as the number of layers increased. —JS Transport measurements indicate superconductivity in twisted trilayers, quadrilayers, and pentalayers of graphene.