Effect of Fermi surface evolution on superconducting gap in superconducting topological insulator

TL;DR

This paper investigates how the evolution of the Fermi surface from three-dimensional to two-dimensional affects the superconducting gap structure and related electronic properties in topological insulators, aiding in understanding their pairing symmetry.

Contribution

It demonstrates the systematic change in the superconducting gap structure with Fermi surface evolution and links bulk electronic properties to Fermi surface shape and gap type.

Findings

Superconducting gap structure varies with Fermi surface shape.

Electronic properties depend on Fermi surface and gap symmetry.

Results guide identification of pairing symmetry in Cu$_x$Bi$_2$Se$_3$.

Abstract

We study bulk electronic states of superconducting topological insulator, which is the promising candidate for topological superconductor. Recent experiments suggest that the three-dimensional Fermi surface evolves into two-dimensional one. We show that the superconducting energy gap structure on the Fermi surface systematically changes with this evolution. It is clarified that the bulk electronic properties such as spin-lattice relaxation rate and specific heat depend on the shape of the Fermi surface and the type of the energy gap function. These results serve as a guide to determine the pairing symmetry of Cu$_x$Bi$_2$Se$_3$.