The unusual properties of superconductivity in magic-angle twisted bilayer graphene (MATBG) have sparked considerable research interest^{1,2,3,4,5,6,7,8,9,10,11,12,13}. However, despite the dedication of intensive experimental efforts and the proposal of several possible pairing mechanisms^{14,15,16,17,18,19,20,21,22,23,24}, the origin of its superconductivity remains elusive. Here, by utilizing angle-resolved photoemission spectroscopy with micrometre spatial resolution, we reveal flat-band replicas in superconducting MATBG, where MATBG is unaligned with its hexagonal boron nitride substrate¹¹. These replicas show uniform energy spacing, approximately 150 ± 15 meV apart, indicative of strong electron–boson coupling. Strikingly, these replicas are absent in non-superconducting twisted bilayer graphene (TBG) systems, either when MATBG is aligned to hexagonal boron nitride or when TBG deviates from the magic angle. Calculations suggest that the formation of these flat-band replicas in superconducting MATBG are attributed to the strong coupling between flat-band electrons and an optical phonon mode at the graphene K point, facilitated by intervalley scattering. These findings, although they do not necessarily put electron–phonon coupling as the main driving force for the superconductivity in MATBG, unravel the electronic structure inherent in superconducting MATBG, thereby providing crucial information for understanding the unusual electronic landscape from which its superconductivity is derived.

魔术角扭曲双层石墨烯 （MATBG） 中超导性的不寻常特性引发了相当大的研究兴趣^{1,2,3,4,5,6,7,8,9,10,11,12,13}。然而，尽管投入了大量的实验工作并提出了几种可能的配对机制^{14、15、16、17、18、19、20、21、22、23、24}，但其超导性的起源仍然难以捉摸。在这里，通过利用具有微米空间分辨率的角度分辨光电子光谱，我们揭示了超导 MATBG 中的平带复制品，其中 MATBG 与其六方氮化硼衬底未对齐¹¹。这些复制品显示出均匀的能量间距，相距约 150 ± 15 meV，表明电子-玻色子耦合很强。引人注目的是，这些复制品在非超导扭曲双层石墨烯 （TBG） 系统中不存在，无论是当 MATBG 与六方氮化硼对齐时，还是当 TBG 偏离魔角时。计算表明，在超导 MATBG 中形成这些平带复制品归因于平带电子与石墨烯 K 点的光学声子模式之间的强耦合，这由间隔散射促进。这些发现虽然不一定将电子-声子耦合作为 MATBG 超导性的主要驱动力，但它们揭示了超导 MATBG 固有的电子结构，从而为理解其超导性来源的不寻常电子景观提供了关键信息。