Nearly flat Andreev bound states in superconductor-topological insulator hybrid structures

Abstract

Exotic excitations arise at the interface between a three-dimensional topological insulator (TI) and superconductors. For example, Majorana fermions with a linear dispersion, $E\sim k$, exist in a short $\pi$ Josephson junction on the TI surface. We show that in these systems, the Andreev bound states spectrum becomes nearly flat at zero energy when the chemical potential is sufficiently away from the Dirac point. The flat dispersion is well approximated by $E\sim k^N$, where $N$ scales with the chemical potential. Similar evolution from linear to flat dispersion also occurs for the subgap spectrum of a periodic superconducting proximity structure, such as a TI surface in contact with a stripe superconductor.

5 pages, 4 figures

References in corpus (6)

• Superconducting proximity effect and Majorana fermions at the surface of a topological insulator
• Chiral tunneling and the Klein paradox in graphene
• Andreev reflection and Klein tunneling in graphene
• Specular Andreev reflection in graphene
• Dimensional crossover in topological matter: Evolution of the multiple Dirac point in the layered system to the flat band on the surface
• Topologically protected flat zero-energy surface bands in non-centrosymmetric superconductors

Cited by in corpus (3)

• Current-phase relation for Josephson effect through helical metal
• A Green's function approach to Topological Insulator junctions with magnetic and superconducting regions
• Transport anisotropy and metal-insulator transition in striped Dirac fermion systems