Electric Field Control of Stacking-Order Solitons in Trilayer Graphene

Trilayer graphene exhibits two low-energy stacking configurations (Bernal and rhombohedral). In graphene flakes with both stacking configurations, the area separating them consists of a localized soliton-like region of strain where one graphene layer shifts by the carbon-carbon bond distance. Under a perpendicular electric field, Bernal-stacked trilayer graphene remains metallic whereas rhombohedrally-stacked trilayer graphene develops a band gap. Consequentially, the electric field modifies the relative energy cost of each stacking configuration, permitting rare control over the crystal structure of a material via only the application of an external electric field. We demonstrate the ability to control the stacking configuration in trilayer graphene via an electric field using scanning tunneling microscopy.