Strong interactions and isospin symmetry breaking in a supermoiré lattice.

In multilayer moiré heterostructures, the interference of multiple twist angles ubiquitously leads to tunable ultralong-wavelength patterns known as supermoiré lattices. However, their impact on the system's many-body electronic phase diagram remains largely unexplored. We present local compressibility measurements revealing numerous incompressible states resulting from supermoiré lattice–scale isospin symmetry breaking driven by strong interactions. By using the supermoiré lattice occupancy as a probe of isospin symmetry, we observed an unexpected doubling of the miniband filling near ν = − 2 , possibly indicating a hidden phase transition or normal-state pairing proximal to the superconducting phase. Our work establishes supermoiré lattices as a tunable parameter for designing quantum phases and as an effective tool for unraveling correlated phenomena in moiré materials. Editor's summary: Moiré superlattices formed by stacking two layers of van der Waals materials have characteristic length scales much longer than the lattice constants of the constituent layers. If another layer is then added on top, a supermoiré lattice can form with an even longer wavelength. Xie et al. studied the influence of this supermoiré potential on the electronic structure of magic-angle twisted trilayer graphene. The researchers used a local probe, a scanning single-electron transistor microscope, that revealed strongly correlated phases caused by the supermoiré potential and not accessible to transport measurements. —Jelena Stajic [ABSTRACT FROM AUTHOR]