Sharp Dirac cone at a buried superconductor/topological insulator interface

We have studied the fully buried interface of a topological insulator, Bi2Se3, with the conventional superconductor Nb. We characterized the chemical reactivity at the interface using core level photoemission spectroscopy. Using ARPES we are able to observe the sharp Dirac cone at the buried interface and characterize its details; including energy positions, band dispersion, and electronic scattering rates. All these measurements are carried out over a wide range of coverages, and set the stage for more advanced studies of this interface.