Layer-Number-Controlled Symmetry Breaking and Surface-State Transport in Rhombohedral Graphene Multilayers

Rhombohedral multilayer graphene hosts layer-polarized flat bands, providing an intriguing platform for correlated and topological states; however, how layer number governs symmetry breaking and surface screening remains elusive. Here, we prepare rhombohedral graphene multilayers and systematically conduct electrical transport measurements. We uncover an unconventional layer dependence of phase transitions: the critical displacement field Dc for the layer-antiferromagnetic-to-semimetal transitions remains nearly constant across tetralayer to hexalayer graphene, whereas Dc for the semimetal-to-layer-polarized-insulator transition increases with layer number, defying unscreened Coulomb interaction models. In hexalayer graphene, surface-state-dominated transport emerges with Landau levels and resistive peaks predominantly controlled by adjacent gates, revealing strong interlayer screening. High magnetic fields further reveal valley-layer-locked Landau levels and dissipative states associated with interlayer backscattering, highlighting the presence of decoupled surface states. Our findings establish the layer number as a key tuning knob for engineering correlated and topological phases in rhombohedral graphene multilayers.