Symmetry breaking and phase transitions in twisted rhombohedral trilayer-bilayer graphene

Moiré superlattice based on rhombohedral graphene is an emerging strongly correlated platform for exploring novel quantum states and phase transitions. Here, we report the observation of symmetry-breaking states and phase transitions in a newly discovered twisted rhombohedral trilayer-bilayer graphene (tRTBG) moiré superlattice. At zero magnetic fields, we observe displacement field-driven resistance jumps and hysteresis loops across the symmetry-breaking phase boundaries, providing evidence for first-order phase transitions. The observation of hysteresis loops driven by out-of-plane and in-plane magnetic fields at the boundaries reveals the lifted spin degeneracy in symmetry-breaking metals and correlated insulators. We further investigate the evolution of symmetry-breaking phases and their phase boundaries under finite magnetic fields, revealing rich competition between states with different symmetries. Our findings uncover the isospin-polarized orders in correlated states and enrich the phase diagram of tRTBG, providing new insights into interaction-driven phases in twisted rhombohedral graphene.