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@ARTICLE{Schffelgen:863096,
      author       = {Schüffelgen, Peter and Rosenbach, Daniel and Pang, Yuan
                      and Kampmeier, Jörn and Luysberg, Martina and Kibkalo,
                      Lidia and Mussler, Gregor and Veldhuis, Dick and Brinkman,
                      Alexander and Lu, Li and Schäpers, Thomas and Grützmacher,
                      Detlev},
      title        = {{S}ignatures of induced superconductivity in
                      {A}l{O}x-capped topological heterostructures},
      journal      = {Solid state electronics},
      volume       = {155},
      issn         = {0038-1101},
      address      = {Oxford [u.a.]},
      publisher    = {Pergamon, Elsevier Science},
      reportid     = {FZJ-2019-03210},
      pages        = {111 - 116},
      year         = {2019},
      abstract     = {In order to access exotic Dirac and Majorana states in
                      (Bi,Sb)-based topological insulators (TIs), the physical
                      surface of those crystals should not be exposed to air.
                      2–3 nm of in situ deposited Al on top of pristine TI
                      thin films immediately oxidizes after taking the sample to
                      ambient conditions. The native AlOx provides a favorable
                      hard capping, which preserves the topological surface states
                      during ex situ device fabrication. Here, we present a
                      process on how to construct superconductor – topological
                      insulator – superconductor (S-TI-S) junctions from in situ
                      capped thin films comprised of 15 nm Sb2Te3 on top of
                      6 nm Bi2Te3. The thicknesses of the Sb2Te3 and the Bi2Te3
                      layer allow us to precisely tune the Fermi level of the
                      upper surface of the Sb2Te3 layer. The challenge is to
                      provide a transparent interface between Sb2Te3 and the
                      superconductive Nb, while assuring an AlOx-capped weak link
                      in between two closely separated Nb electrodes. Low
                      temperature experiments on our junctions provide evidence
                      for charge transport mediated by coherent Andreev states.
                      Magnetic field dependent measurements yielded
                      Fraunhofer-like patterns, whose periodicities are in good
                      agreement with the effective areas of the respective
                      junctions. Transmission electron micrographs of the
                      narrowest junction confirm a crystalline and capped weak
                      link. Our results provide the first reported signatures of
                      induced superconductivity in S-TI-S junctions, which are
                      capped by native AlOx. The presented process allows for
                      accessing S-TI hybrid devices via magnetic flux, while
                      assuring in situ conserved weak links. This makes
                      as-prepared junctions a promising platform for proposed
                      flux-controllable Majorana devices.},
      cin          = {PGI-9 / ER-C-1},
      ddc          = {620},
      cid          = {I:(DE-Juel1)PGI-9-20110106 / I:(DE-Juel1)ER-C-1-20170209},
      pnm          = {522 - Controlling Spin-Based Phenomena (POF3-522)},
      pid          = {G:(DE-HGF)POF3-522},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000466840600016},
      doi          = {10.1016/j.sse.2019.03.003},
      url          = {https://juser.fz-juelich.de/record/863096},
}