Electronic structure of a superconducting topological insulator Sr-doped Bi2Se3

TL;DR

This study investigates the electronic structure of Sr-doped Bi2Se3 using advanced spectroscopy and microscopy, revealing topological surface states and Fermi level shifts that suggest potential for topological superconductivity.

Contribution

It provides detailed experimental insights into the electronic structure and surface states of Sr-doped Bi2Se3, highlighting its promise as a topological superconductor.

Findings

Fermi level shifts upward with Sr doping

Topological surface state remains well separated from bulk bands

Persistence of topological surface state indicates potential for topological superconductivity

Abstract

Using high-resolution angle-resolved photoemission spectroscopy and scanning tunneling microscopy/spectroscopy, the atomic and low energy electronic structure of the Sr-doped superconducting topological insulators (SrxBi2Se3) was studied. Scanning tunneling microscopy shows that most of the Sr atoms are not in the van der Waals gap. After Sr doping, the Fermi level was found to move further upwards when compared with the parent compound Bi2Se3, which is consistent with the low carrier density in this system. The topological surface state was clearly observed, and the position of the Dirac point was determined in all doped samples. The surface state is well separated from the bulk conduction bands in the momentum space. The persistence of separated topological surface state combined with small Fermi energy makes this superconducting material a very promising candidate for the time reversal invariant topological superconductor