Drive the Dirac Electrons into Cooper Pairs in SrxBi2Se3

Abstract

Topological superconductor is a very interesting and frontier topic in condensed matter physics1. Despite the tremendous efforts in exploring the topological superconductivity, its presence is however still under heavy debates. The Dirac electrons are supposed to exist in a thin layer of the surface of a topological insulator. Due to the finite spin-orbital coupling, these electrons will have a spin-momentum locking effect. In this case, the superfluid with the spin singlet Cooper pairing is not completely comforted by the Dirac electrons. It thus remains unclear whether and how the Dirac electrons fall into Cooper pairing in an intrinsic superconductor with the topological surface states. In this work, we show the systematic study of scanning tunneling microscope/spectroscopy on the possible topological superconductor SrxBi2Se3. We first show that only the intercalated (or inserted), not the substituted Sr atoms can induce superconductivity. Then we show the full superconducting gaps without any abnormal in-gap density of states as expected theoretically for the bulk topological superconductivity. However, we find that the surface Dirac electrons will simultaneously condense into the superconducting state when the energy is smaller than the bulk superconducting gap. This vividly demonstrates how the surface Dirac electrons are driven into Cooper pairs.

arXiv comment28 pages, 7 figures, including Supplementary Information

References in corpus (35)

• Topological Insulators
• Topological insulators and superconductors
• Superconducting proximity effect and Majorana fermions at the surface of a topological insulator
• Signatures of Majorana fermions in hybrid superconductor-semiconductor nanowire devices
• Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class with spin-polarized single-Dirac-cone on the surface
• Observation of Majorana Fermions in Ferromagnetic Atomic Chains on a Superconductor
• Superconductivity in CuxBi2Se3 and its implications for pairing in the undoped topological insulator
• Odd-Parity Topological Superconductors: Theory and Application to Cu${}_x$Bi${}_2$Se${}_3$
• Topological Superconductivity in CuxBi2Se3
• Majorana mode in vortex core of Bi2Te3/NbSe2 topological insulator-superconductor heterostructure
• The Coexistence of Superconductivity and Topological Order in the Bi2Se3 Thin Films
• Coexistence of the topological state and a two-dimensional electron gas on the surface of Bi2Se3
• Observation of topological order in a Superconducting doped topological insulator (based on the Bi2Se3 class)
• Landau Quantization of Massless Dirac Fermions in Topological Insulator
• Quantum interference in macroscopic crystals of non-metallic Bi${}_2$Se${}_3$
• Spin-Rotation Symmetry Breaking in the Superconducting State of CuxBi2Se3
• Observation of Dirac node formation and mass acquisition in a topological crystalline insulator
• Momentum-Resolved Landau-Level Spectroscopy of Dirac Surface State in Bi2Se3
• Thermodynamic evidence for nematic superconductivity in Cu${}_x$Bi${}_2$Se${}_3$
• Superconductivity with topological surface state in SrxBi2Se3
• Landau quantization and the thickness limit of topological insulator thin films of Sb2Te3
• Odd-parity topological superconductor with nematic order: Application to CuxBi2Se3
• Local Measurements of the Superconducting Pairing Symmetry in CuxBi2Se3
• Odd-Parity Pairing and Topological Superconductivity in a Strongly Spin-Orbit Coupled Semiconductor
• Superconducting Topological Surface States in Non-centrosymmetric Bulk Superconductor PbTaSe2
• Majorana Fermions and Exotic Surface Andreev Bound States in Topological Superconductors: Application to CuxBi2Se3
• Tunneling Conductance and Surface States Transition in Superconducting Topological Insulators
• Dirac Surface States and Nature of Superconductivity in Noncentrosymmetric BiPd
• Unconventional superconductivity in CuxBi2Se3
• Electronic structure of a superconducting topological insulator Sr-doped Bi2Se3
• Multiple nodeless superconducting gaps in noncentrosymmetric superconductor PbTaSe2 with topological bulk nodal lines
• Visualizing Landau levels of Dirac electrons in a one dimensional potential
• Fully gapped superconductivity in In-doped topological crystalline insulator Pb${}_{0.5}$Sn${}_{0.5}$Te
• Electronic structure and relaxation dynamics in a superconducting topological material
• Superconductivity by Sr Intercalation in Layered Topological Insulator Bi2Se3

Cited by in corpus (26)

• Superconducting Topological Surface States in Non-centrosymmetric Bulk Superconductor PbTaSe2
• Nematic superconductivity in doped Bi2Se3 topological superconductors
• Direct visualization of the nematic superconductivity in Cu${}_x$Bi${}_2$Se${}_3$
• A comprehensive review on topological superconducting materials and interfaces
• Structural distortion behind the nematic superconductivity in Sr${}_x$Bi${}_2$Se${}_3$
• Approaching the Type-II Dirac Point and Concomitant Superconductivity in Pt-doping Stabilized Metastable 1T-phase IrTe2
• Pressure-induced Superconductivity in the Three-component Fermion Topological Semimetal Molybdenum Phosphide
• Electron-phonon superconductivity in CaBi2 and the role of spin-orbit interaction
• Possible structural origin of superconductivity in Sr-doped Bi2Se3
• Dirac lines and loop at the Fermi level in the Time-Reversal Symmetry Breaking Superconductor LaNiGa${}_2$
• Evidence for singular-phonon-induced nematic superconductivity in a topological superconductor candidate Sr${}_{0.1}$Bi${}_2$Se${}_3$
• Direct Evidence for Time-Reversal Symmetry Breaking in Topological Superconductor Sr0.1Bi2Se3
• Link between superconductivity and a Lifshitz transition in intercalated Bi${}_2$Se${}_3$
• Low-energy excitations and non-BCS superconductivity in Nb${}_x$-Bi${}_2$Se${}_3$
• Twofold symmetry of proximity-induced superconductivity in Bi${}_2$Te${}_3$/Bi${}_2$Sr${}_2$CaCu${}_2$O${}_{8+\delta }$ heterostructures revealed by scanning tunneling microscopy
• Effect of Sr doping on structure, morphology and transport properties of Bi${}_2$Se${}_3$ epitaxial thin films
• Observability of superconductivity in Sr-doped Bi2Se3 at the surface using scanning tunneling microscope
• Structural and magneto-transport studies of iron intercalated Bi2Se3 single crystals
• Quasiparticle interference in doped topological insulators with nematic superconductivity
• An increase in $T_c$ under hydrostatic pressure in the superconducting doped topological insulator Nb${}_{0.25}$Bi${}_2$Se${}_3$
• Scanning tunneling spectroscopy investigations of superconducting-doped topological insulators: Experimental pitfalls and results
• Superconductivity induced by Ag intercalation in Dirac semimetal Bi${}_2$Se${}_3$
• Visualizing Pairing Symmetry in Nematic Superconductors using spin-polarized spectroscopy of magnetic impurities
• Topological properties of finite-size heterostructures of magnetic topological insulators and superconductors
• Superconductivity and vortex structure on Bi${}_2$Te${}_3$/FeTe${}_{0.55}$Se${}_{0.45}$ heterostructures with different thickness of Bi${}_2$Te${}_3$ films
• Possible two-component pairings in electron-doped Bi${}_2$Se${}_3$ based on a tight-binding model