Interface and scattering potentials in topological insulator-superconductor heterostructures

Many proposed applications of topological insulators rely on coupling them to superconductors in Josephson-type geometry. However, interface potentials at the boundary between a superconductor and a topological insulator can alter the dispersion and the spin texture of the topological states, thereby changing the nature of the proximity-induced superconducting order. Using effective low-energy models we study how these potentials, combined with the scattering at lateral junctions between superconducting and non-superconducting regions, change the spectra of the Andreev bound states and the Josephson current-phase relationship. We discuss the relevance of our findings to proposals for functional heterostructures.