Robust superconductivity in magic-angle multilayer graphene family
Robust superconductivity in magic-angle multilayer graphene family
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DOI：
10.1038/s41563-022-01287-1
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发表时间：
2022-07-07
期刊：
影响因子：
41.2
通讯作者：
Jarillo-Herrero, Pablo
中科院分区：
文献类型：
--
作者：
Park, Jeong Min;Cao, Yuan;Jarillo-Herrero, Pablo
在魔角扭曲的四层和五层石墨烯系统中报道了超导性。虽然他们发现所有魔角石墨烯系统都符合统一的系统层次结构，在其电子能带结构中共享一组平带，但他们还报告说，魔角扭曲双层石墨烯和其他家族成员之间存在关键区别，这与磁场中电子在层间运动的方式不同有关。魔-角扭曲双层石墨烯（MATBG）为探索相互作用驱动和拓扑现象建立了一个新的平台。然而，尽管在莫尔系统中观察到大量的相关相，但稳健的超导性似乎最不常见，仅在MATBG和最近的魔角扭曲三层石墨烯中发现。在这里，我们报告的超导魔角扭曲四层和五层石墨烯的实验实现，从而建立交替扭曲魔角多层石墨烯作为一个强大的家庭莫尔超导体。这一发现表明，成员共享的平带在超导性中起着核心作用。我们在平行磁场中的测量，特别是对泡利极限破坏和自发旋转对称破缺的研究，揭示了N = 2和N > 2层结构之间的明显区别，这与它们对磁场的轨道响应之间的差异一致。我们的研究结果扩展了莫尔超导体的新兴家族，为设计新的超导材料平台提供了新的见解和潜在的影响。
Superconductivity is reported in magic-angle twisted four-layer and five-layer graphene systems. While they find that all magic-angle graphene systems fit into a unified hierarchy of systems that share a set of flat bands in their electronic band structures, they also report that there is a key distinction between magic-angle twisted bilayer graphene and the other family members, related to the difference in the way the electrons move between the layers in a magnetic field.The discovery of correlated states and superconductivity in magic-angle twisted bilayer graphene (MATBG) established a new platform to explore interaction-driven and topological phenomena. However, despite multitudes of correlated phases observed in moire systems, robust superconductivity appears the least common, found only in MATBG and more recently in magic-angle twisted trilayer graphene. Here we report the experimental realization of superconducting magic-angle twisted four-layer and five-layer graphene, hence establishing alternating twist magic-angle multilayer graphene as a robust family of moire superconductors. This finding suggests that the flat bands shared by the members play a central role in the superconductivity. Our measurements in parallel magnetic fields, in particular the investigation of Pauli limit violation and spontaneous rotational symmetry breaking, reveal a clear distinction between the N = 2 and N > 2-layer structures, consistent with the difference between their orbital responses to magnetic fields. Our results expand the emergent family of moire superconductors, providing new insight with potential implications for design of new superconducting materials platforms.