Print Email Facebook Twitter Scanning tunneling spectroscopy investigations of superconducting-doped topological insulators Title Scanning tunneling spectroscopy investigations of superconducting-doped topological insulators: Experimental pitfalls and results Author Wilfert, Stefan (University of Würzburg) Sessi, Paolo (University of Würzburg) Wang, Zhiwei (University of Cologne) Schmidt, Henrik (University of Würzburg) Martinez Velarte, M.C. (TU Delft QN/Otte Lab) Lee, S.H. (The Pennsylvania State University; Missouri University of Science and Technology) Hor, Yew San (Missouri University of Science and Technology) Otte, A. F. (TU Delft QN/Otte Lab) Ando, Yoichi (University of Cologne) Wu, Weida (Rutgers University; University of Würzburg) Bode, Matthias (University of Würzburg) Date 2018 Abstract Recently, the doping of topological insulators has attracted significant interest as a potential route towards topological superconductivity. Because many experimental techniques lack sufficient surface sensitivity, however, definite proof of the coexistence of topological surface states and surface superconductivity is still outstanding. Here we report on highly surface sensitive scanning tunneling microscopy and spectroscopy experiments performed on Tl-doped Bi2Te3, a three-dimensional topological insulator which becomes superconducting in the bulk at TC=2.3 K. Landau level spectroscopy as well as quasiparticle interference mapping clearly demonstrated the presence of a topological surface state with a Dirac point energy ED=-(118±1) meV and a Dirac velocity vD=(4.7±0.1)×105 m/s. Tunneling spectra often show a superconducting gap, but temperature- and field-dependent measurements show that both TC and μ0HC strongly deviate from the corresponding bulk values. Furthermore, in spite of a critical field value which clearly points to type-II superconductivity, no Abrikosov lattice could be observed. Experiments performed on normal-metallic Ag(111) prove that the gapped spectrum is caused only by superconducting tips, probably caused by a gentle crash with the sample surface during approach. Nearly identical results were found for the intrinsically n-type compound Nb-doped Bi2Se3. Our results suggest that the superconductivity in superconducting-doped V-VI topological insulators does not extend to the surface where the topological surface state is located. To reference this document use: http://resolver.tudelft.nl/uuid:193eed47-c6fa-4093-8736-cbaef8af2915 DOI https://doi.org/10.1103/PhysRevB.98.085133 ISSN 2469-9950 Source Physical Review B, 98 (8) Part of collection Institutional Repository Document type journal article Rights © 2018 Stefan Wilfert, Paolo Sessi, Zhiwei Wang, Henrik Schmidt, M.C. Martinez Velarte, S.H. Lee, Yew San Hor, A. F. Otte, Yoichi Ando, Weida Wu, Matthias Bode Files PDF PhysRevB.98.085133.pdf 1.07 MB Close viewer /islandora/object/uuid:193eed47-c6fa-4093-8736-cbaef8af2915/datastream/OBJ/view