Moiré nematic phase in twisted double bilayer graphene

Graphene moir\'e superlattices display electronic flat bands. At integer fillings of these bands, energy gaps due to strong electron-electron interactions are generally observed. However, the presence other correlation-driven phases in twisted graphitic systems at non-integer is unclear. Here, we report scanning tunneling microscopy (STM) measurements that reveal existence threefold rotational (C3) symmetry breaking double bilayer graphene (tDBG). Using spectroscopic imaging over large and uniform areas characterize direction degree C3 breaking, find it be prominent only energies corresponding bands nearly absent remote We demonstrate cannot explained by heterostrain or displacement field, instead a manifestation an interaction-driven nematic phase, which emerges even away from fillings. Comparing our experimental data with combination microscopic phenomenological modeling, show instability not associated local scale lattice, but emergent phenomenon pointing universal character this ordered state band materials.