Observability of superconductivity in Sr-doped Bi2Se3 at the surface using scanning tunneling microscope

Abstract

The superconducting materials family of doped Bi2Se3 remains intensively studied in the field of condensed matter physics due to strong experimental evidence for topologically non-trivial superconductivity in the bulk. However, at the surface of these materials, even the observation of superconductivity itself is still controversial. We use scanning tunneling microscopy (STM) down to 0.4 K to show that on the surface of bulk superconducting SrxBi2Se3, no gap in the density of states is observed around the Fermi energy as long as clean metallic probe tips are used. Nevertheless, using scanning electron microscopy and energy-dispersive X-ray analysis, we find that micron-sized flakes of SrxBi2Se3 are easily transferred from the sample onto the STM probe tip and that such flakes consistently show a superconducting gap in the density of states. We argue that the superconductivity in SrxBi2Se3 crystals does not extend to the surface when the topological surface state (TSS) is intact, but in micro-flakes the TSS has been destroyed due to strain and allows the superconductivity to extend to the surface. To understand this phenomenon, we propose that the local electric field, always found in electron doped Bi2Se3 in the presence of the TSS due to an intrinsic upward band bending, works against superconductivity at the surface.

arXiv comment13 pages, 8 figures, to appear in Phys. Rev. Materials

References in corpus (36)

• Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class with spin-polarized single-Dirac-cone on the surface
• Topological superconductors: a review
• 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${}_3$
• Hexagonal Warping Effects in the Surface States of Topological Insulator Bi${}_2$Te${}_3$
• Experimental demonstration of the topological surface states protected by the time-reversal symmetry
• Topological Crystalline Insulators and Topological Superconductors: From Concepts to Materials
• Bulk Fermi surface coexistence with Dirac surface state in Bi${}_2$Se${}_3$: a comparison of photoemission and Shubnikov-de Haas measurements
• Landau Quantization of Massless Dirac Fermions in Topological Insulator
• Spin-Rotation Symmetry Breaking in the Superconducting State of CuxBi2Se3
• Thermodynamic evidence for nematic superconductivity in Cu${}_x$Bi${}_2$Se${}_3$
• Superconductivity with topological surface state in SrxBi2Se3
• Local Measurements of the Superconducting Pairing Symmetry in CuxBi2Se3
• Rashba spin-splitting control at the surface of the topological insulator Bi2Se3
• Berry phase of non-ideal Dirac fermions in topological insulators
• Metallic supercurrent field-effect transistor
• Electrochemical synthesis and superconducting phase diagram of Cu_xBi2Se3
• Nematic superconductivity in doped Bi2Se3 topological superconductors
• Power-Law Decay of Standing Waves on the Surface of Topological Insulators
• Direct visualization of the nematic superconductivity in Cu${}_x$Bi${}_2$Se${}_3$
• Structural distortion behind the nematic superconductivity in Sr${}_x$Bi${}_2$Se${}_3$
• Electronic structure of a superconducting topological insulator Sr-doped Bi2Se3
• Drive the Dirac Electrons into Cooper Pairs in SrxBi2Se3
• Generalized Anderson's theorem for superconductors derived from topological insulators
• Work function of bulk-insulating topological insulator Bi2-xSbxTe3-ySey
• Sauter-Schwinger effect in a Bardeen-Cooper-Schrieffer superconductor
• Spin-orbital groundstates of Superconducting doped topological insulators (A Majorana Platform)
• Possible structural origin of superconductivity in Sr-doped Bi2Se3
• Trigger of the ubiquitous surface band bending in 3D topological insulators
• Nematic Superconductivity in Cu1.5(PbSe)5(Bi2Se3)6
• Electronic structure and relaxation dynamics in a superconducting topological material
• Band bending at the surface of Bi${}_2$Se${}_3$ studied from first principles
• Low-energy excitations and non-BCS superconductivity in Nb${}_x$-Bi${}_2$Se${}_3$
• The Vertical Position of Sr Dopants in the Sr${}_x$Bi${}_2$Se${}_3$ Superconductor
• Intrinsic surface dipole in topological insulators
• Scanning tunneling spectroscopy investigations of superconducting-doped topological insulators: Experimental pitfalls and results

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• Atomic Visualization of Bulk and Surface Superconductivity in Weyl Semimetal γ-PtBi2
• Quasiparticle interference on the surface of Bi${}_2$Se${}_3$ terminated (PbSe)${}_5$(Bi${}_2$Se${}_3$)${}_6$