Resolving intervalley gaps and many-body resonances in moiré superconductors

Magic-angle twisted multilayer graphene stands out as a highly tunable class of moiré materials that exhibit strong electronic correlations and robust superconductivity^1-4. However, understanding the relationships between the low-temperature superconducting phase and the preceding correlated parent states remains a challenge. Here we use scanning tunnelling microscopy (STM) and spectroscopy to track the formation sequence of correlated phases established by the interplay of dynamic correlations, intervalley coherence and superconductivity in magic-angle twisted trilayer graphene (MATTG). We discover the existence of two well-resolved gaps pinned at the Fermi level within the superconducting doping range. Although the outer gap, previously associated with the pseudogap phase^5,6, persists at high temperatures and magnetic fields, the newly revealed inner gap is more fragile, in line with previous transport experiments^1,2,4. Andreev reflection spectroscopy taken at the same location confirms a clear trend that closely follows the doping behaviour of the inner gap and not the outer one. Moreover, spectroscopy taken at nanoscale domain boundaries further corroborates the contrasting behaviour of the two gaps, with the inner gap remaining resilient to structural variations. By comparing our results with recent topological heavy fermion (THF) models that include dynamical correlations^7,8, we find that the outer gap probably arises from a splitting of the Abrikosov-Suhl-Kondo resonance^9,10 owing to the breaking of the valley symmetry. Our results indicate an intricate yet tractable hierarchy of correlated phases in twisted multilayer graphene.