Superconducting Topological Surface States in Non-centrosymmetric Bulk Superconductor PbTaSe2

TL;DR

This paper reports the visualization of topological surface states in the superconductor PbTaSe2, revealing its potential as a topological superconductor with implications for quantum computing.

Contribution

It provides the first atomic-scale visualization of topological surface states in a non-centrosymmetric, fully gapped superconductor, identifying PbTaSe2 as a promising TSC candidate.

Findings

Two topological surface states with a Dirac point at ~1.0 eV were observed.

Inner TSS and part of outer TSS cross the Fermi level on the Pb-terminated surface.

PbTaSe2 exhibits fully gapped bulk superconductivity with topological surface states.

Abstract

The search for topological superconductors (TSCs) is one of the most urgent contemporary problems in condensed matter systems. TSCs are characterized by a full superconducting gap in the bulk and topologically protected gapless surface (or edge) states. Within each vortex core of TSCs, there exist the zero energy Majorana bound states, which are predicted to exhibit non-Abelian statistics and to form the basis of the fault-tolerant quantum computation. So far, no stoichiometric bulk material exhibits the required topological surface states (TSSs) at Fermi level combined with fully gapped bulk superconductivity. Here, we report atomic scale visualization of the TSSs of the non-centrosymmetric fully-gapped superconductor, PbTaSe2. Using quasiparticle scattering interference (QPI) imaging, we find two TSSs with a Dirac point at E~1.0eV, of which the inner TSS and partial outer TSS cross Fermi level, on the Pb-terminated surface of this fully gapped superconductor. This discovery reveals PbTaSe2 as a promising candidate as a TSC.