Robust superconductivity in magic-angle multilayer graphene family

• Published in: Nature materials Vol. 21; no. 8; pp. 877 - 883
• Main Authors: Park, Jeong Min, Cao, Yuan, Xia, Li-Qiao, Sun, Shuwen, Watanabe, Kenji, Taniguchi, Takashi, Jarillo-Herrero, Pablo
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.08.2022; Nature Publishing Group; Springer Nature
• Subjects: 639/766/119/1003; 639/766/119/995; Banded structure; Bilayers; Biomaterials; Broken symmetry; Chemistry; Chemistry and Materials Science; Condensed Matter Physics; Graphene; Magnetic fields; Materials Science; Multilayers; Nanotechnology; Optical and Electronic Materials; Physics; Robustness; Superconductivity; Superconductors
• ISSN: 1476-1122; 1476-4660; 1476-4660
• DOI: 10.1038/s41563-022-01287-1

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 moiré 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 moiré 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 moiré superconductors, providing new insight with potential implications for design of new superconducting materials platforms. 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.