Topological Dirac surface states and superconducting pairing correlations in PbTaSe 2
Topological Dirac surface states and superconducting pairing correlations in PbTaSe 2
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DOI：
10.1103/physrevb.93.245130
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发表时间：
2015-11
影响因子：
3.7
通讯作者：
Tay-Rong Chang;Peng Chen;G. Bian;Shin-Ming Huang;Hao Zheng;T. Neupert;R. Sankar;Su-Yang Xu
中科院分区：
文献类型：
--
作者：
Tay-Rong Chang;Peng Chen;G. Bian;Shin-Ming Huang;Hao Zheng;T. Neupert;R. Sankar;Su-Yang Xu
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 ${\mathrm{PbTaSe}}_{2}$, a noncentrosymmetric superconductor, possesses a nonzero ${\mathbb{Z}}_{2}$ topological invariant and fully spin-polarized Dirac surface states. Moreover, we analyze the phonon spectrum of ${\mathrm{PbTaSe}}_{2}$ 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 ${\mathrm{PbTaSe}}_{2}$ 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.
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 ${\mathrm{PbTaSe}}_{2}$, a noncentrosymmetric superconductor, possesses a nonzero ${\mathbb{Z}}_{2}$ topological invariant and fully spin-polarized Dirac surface states. Moreover, we analyze the phonon spectrum of ${\mathrm{PbTaSe}}_{2}$ 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 ${\mathrm{PbTaSe}}_{2}$ 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.