Termination-dependent Superconducting Topological Surface States in Non-centrosymmetric PbTaSe₂

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, PbTaSe₂ is the only stoichiometric bulk material exhibits the required topological surface states at E_F combined with fully gapped bulk superconductivity [1]. Interestingly, two distinct and stable cleaved surfaces have been identified to be Pb- and Se-termination by using spectroscopic imaging-scanning tunneling microscope. Two terminations exhibit striking difference in both atomic and electronic structures above Tc. In the superconducting state, both exhibit a full superconducting gap and zero energy bound state in the superconducting vortex cores. Our results show PbTaSe₂ is a great platform for the study of 2D TSC.
[1] S.Y. Guan et al., Sci. Adv. 2, e1600894 (2016)