Topological Dirac surface states and superconducting pairing correlations in PbTaSe2

Tay Rong Chang, Peng Jen Chen, Guang Bian, Shin Ming Huang, Hao Zheng, Titus Neupert, Raman Sankar, Su Yang Xu, Ilya Belopolski, Guoqing Chang, Baokai Wang, Fangcheng Chou, Arun Bansil, Horng Tay Jeng, Hsin Lin, M. Zahid Hasan

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42 Citations (Scopus)

Abstract

Superconductivity in topological band structures is a platform for realizing Majorana bound states and other exotic physical phenomena such as emergent supersymmetry. This potential nourishes the search for topological materials with intrinsic superconducting instabilities, in which Cooper pairing is introduced to electrons with helical spin texture such as the Dirac surface states of topological insulators, forming a time-reversal symmetric topological superconductor on the surface. We employ first-principles calculations and angle-resolved photoemission spectroscopy experiments to reveal that PbTaSe2, a noncentrosymmetric superconductor, possesses a nonzero Z2 topological invariant and fully spin-polarized Dirac surface states. Moreover, we analyze the phonon spectrum of PbTaSe2 to show how superconductivity emerges in this compound due to a stiffening of phonons by the Pb intercalation, which diminishes a competing charge-density-wave instability. By combining our findings on the topological band structure and the superconducting electron pairing, our work establishes PbTaSe2 as a stoichiometric superconductor with topological Dirac surface states. This type of intrinsic topological Dirac superconductors holds great promise for studying aspects of topological superconductors such as Majorana zero modes.

Original languageEnglish
Article number245130
JournalPhysical Review B
Volume93
Issue number24
DOIs
Publication statusPublished - 2016 Jun 14

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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    Chang, T. R., Chen, P. J., Bian, G., Huang, S. M., Zheng, H., Neupert, T., Sankar, R., Xu, S. Y., Belopolski, I., Chang, G., Wang, B., Chou, F., Bansil, A., Jeng, H. T., Lin, H., & Hasan, M. Z. (2016). Topological Dirac surface states and superconducting pairing correlations in PbTaSe2. Physical Review B, 93(24), [245130]. https://doi.org/10.1103/PhysRevB.93.245130