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

Syu-You Guan^1,2*, Peng-Jen Chen^1,2,3, Ming-Wen Chu⁴, Raman Sankar^2,4, Fangcheng Chou⁴, Horng-Tay Jeng^2,5, Chia-Seng Chang^1,2, Tien-Ming Chuang²

¹Department of Physics, National Taiwan University, Taipei, Taiwan
²Institute of Physics, Academia Sinica, Taipei, Taiwan
³Nano Science and Technology Program, TIGP, Academia Sinica, Taipei, Taiwan
⁴Center for Condensed Matter Sciences, National Taiwan University, Taipei, Taiwan
⁵Department of Physics, National Tsing Hua University, Hsinchu, Taiwan

* Presenter:Syu-You Guan, email:r95222038@gmail.com

The search for topological superconductors (TSCs) is one of the most exciting subjects in condensed matter physics. 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. So far, PbTaSe2 is the only stoichiometric bulk material exhibits the required topological surface states at EF combined with fully gapped bulk superconductivity1. Interestingly, two distinct and stable terminations have been identified to be Pb- and Se-surface by using spectroscopic imaging-scanning tunneling microscope. Two terminations exhibit striking difference in both atomic and electronic structure above Tc while both exhibit a full superconducting gap and zero energy bound state in the superconducting vortex core2. Our results show PbTaSe2 is a great platform for the study of 2D TSC.

Keywords: STM, Topological surface state, Superconductor