Proximity effect at the superconductor - topological insulator interface

Understand

We study the excitation spectrum of a topological insulator in contact with an s-wave superconductor, starting from a microscopic model, and develop an effective low-energy model for the proximity effect.

• In the vicinity of the Dirac cone vertex, the effective model describing the states localized at the interface is well approximated by a model of Dirac electrons experiencing superconducting s-wave pairing.
• Away from the cone vertex, the induced pairing potential develops a p-wave component with a magnitude sensitive to the structure of the interface.
• Observing the induced s-wave superconductivity may require tuning the chemical potential close to the Dirac point.