Posters

Confining two-dimensional Dirac fermions is a conceptual and practical challenge. It can be achieved, in principle, by introducing magnetism to the surfaces of a topological insulator, or in Graphene using intricate techniques of fabrications, electrostatic gating, and coupling to superconductivity. However, these are all complex methods that require external fields or materials. In this work, we show that Dirac fermion confinement appears naturally on the surfaces of topological crystalline insulators (TCIs), which host multiple surface Dirac cones, depending on the surface terminations and the symmetries they preserve or break. This confinement is most dramatically reflected in the flux dependence of the surface states of a TCI in a nanowire geometry, where different facets of the wire connect to form a closed surface. Using SnTe as a case study, we show how wires with all four facets of the type display novel Aharonov-Bohm oscillations that imply an extended nature of the surface states, while in nanowires with four facets of the type, such oscillations are absent due to the strong confinement of the Dirac states to each facet separately. Our results place TCI nanowires as a versatile platform for confining and manipulating Dirac surface states.