Surface spectral function in the superconducting state of a topological insulator

Abstract

We discuss the surface spectral function of superconductors realized from a topological insulator, such as the copper-intercalated Bi${}_{2}$Se${}_{3}$. These functions are calculated by projecting bulk states to the surface for two different models proposed previously for the topological insulator. Dependence of the surface spectra on the symmetry of the bulk pairing order parameter is discussed with particular emphasis on the odd-parity pairing. Exotic spectra such as an Andreev bound state connected to the topological surface states are presented.