Quantifying superconducting proximity pairing in topological (Bi<sub>1-x</sub>Sb<sub>x</sub>)<sub>2</sub>Te<sub>3</sub> films on niobium substrates

ORAL

Abstract

Topological insulator films proximally coupled to simple isotropic superconductors are theoretically promising candidates for the 2D topological superconductor phase with exotic emergent phenomena, but fabricating these systems is often exceedingly difficult. By employing a novel cleavage-based “flip-chip” technique, we report the fabrication of single-crystalline (Bi1-xSbx)2Te3 thin films (x = 0 to 1) with predetermined layer thicknesses (2-10 layers) on superconducting Nb. While bulk conducting topological Bi2Se3 films interfaced with Nb films exhibit strong superconducting order in the nontrivial surface states, bulk insulating topological (Bi1-xSbx)2Te3 films on Nb (x = 0.62) instead show a massive suppression of proximity pairing at the surface, even for films only two layers in thickness. This giant attenuation of surface superconductivity is revealed by our recent ultrahigh-resolution band mappings and clarified by our ongoing scanning tunneling spectroscopy measurements, the results of which are compared with those of bulk conducting n-doped topological Bi2Se3/Nb and Bi2Te3/Nb. The results further highlight the design constraints of employing the superconducting proximity effect to generate topological superconductivity in nearly intrinsic systems.

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Presenters

  • Joseph Hlevyack

    • University of Illinois at Urbana-Champaign

Authors

  • Joseph Hlevyack

    • University of Illinois at Urbana-Champaign

  • Sahand Najafzadeh

    • Institute for Solid State Physics, University of Tokyo

  • Meng-Kai Lin

    • University of Illinois at Urbana-Champaign

  • Takahiro Hashimoto

    • Institute for Solid State Physics, University of Tokyo

  • Tsubaki Nagashima

    • Institute for Solid State Physics, University of Tokyo

  • Akihiro Tsuzuki

    • Institute for Solid State Physics, University of Tokyo

  • Akiko Fukushima

    • Institute for Solid State Physics, University of Tokyo

  • Cédric Bareille

    • Institute for Solid State Physics, University of Tokyo

  • Yen-Chen Tsui

    • Institute of Physics, Academia Sinica

  • Syu-You Guan

    • Institute of Physics, Academia Sinica

  • Wen-Yu Chen

    • Institute of Physics, Academia Sinica

  • Yang Bai

    • University of Illinois at Urbana-Champaign

  • Peng Chen

    • Shanghai Jiao Tong University

  • Ro-Ya Liu

    • National Synchrotron Radiation Research Center

  • Yao Li

    • University of Illinois at Urbana-Champaign

  • David Floetotto

    • University of Illinois at Urbana-Champaign

  • José Avila

    • Synchrotron SOLEIL

  • Sung-Kwan Mo

    • Lawrence Berkeley National Laboratory
    • Advanced Light Source, Lawrence Berkeley National Laboratory
    • Advanced Light Source

  • James Eckstein

    • Department of Physics and Materials Research Lab, University of Illinois at Urbana-Champaign
    • University of Illinois at Urbana-Champaign

  • Tien-Ming Chuang

    • Institute of Physics, Academia Sinica
    • Institute of Physics, Academia Sinica Taipei

  • Shik Shin

    • Institute for Solid State Physics, University of Tokyo

  • Kozo Okazaki

    • Institute for Solid State Physics, University of Tokyo

  • Tai-Chang Chiang

    • University of Illinois at Urbana-Champaign