Robust Reflection Asymmetry Across Rhombohedral–Bernal Stacking Boundaries in Trilayer Graphene

We report a pronounced direction-dependent quantum transport phenomenon across stacking domain boundaries in trilayer graphene, revealed by large-scale wave packet dynamics simulations. Employing molecular statics with realistic interatomic force fields, we construct an ABC–ABA grain boundary geometry with structural features – such as soliton width and corrugation amplitude – that closely match experimental observations. To mimic a transport device geometry, we injected electrons from a graphene electrode into the outer layer of our ABC-ABA junction. We demonstrate that this configuration shows a striking asymmetry in transport behavior: wave packets incident from the rhombohedral (ABC) side transmit with minimal reflection, while those originating from the Bernal (ABA) side are strongly backscattered. The total reflection probability measured in the graphene electrode differs by more than a factor of 20 between the two incidence directions, and the energy-dependent transmission function reveals that the main differences are concentrated within
the ±0.5 eV energy range around the Fermi level. We prove that this rectification is robust across grain boundaries of varying thicknesses and morphologies, as it originates from the distinct electronic structures – effective masses, sublattice-, and layer polarizations – of the two stacking configurations. These differences in
the electronic structure of the two stacking configurations are rooted in their lattice symmetries: the mirrorsymmetric ABA and the inversion-symmetric ABC trilayers, which give rise to distinct reflection behavior at both the graphene-trilayer contact and the ABA–ABC grain boundary. The precise energy dependence of the reflection function, however, depends on the specific atomic structure of the domain boundary, yet, without altering the overall value of the reflection. Our results show that contacted ABC–ABA stacking domain
boundaries could lead to directional quantum transport — opening a pathway toward quantum diode-like functionalities.