Proximity induced superconductivity in Bi$_2$Se$_3$ nanoribbons

ORAL

Abstract

Proposals for possible realizations of Majorana fermions in condensed matter provide a strong motivation for interfacing superconductors with topological insulators (PRL {\bf 100}, 096407 (2008)). We describe experiments that accomplish an important first step in this context: the realization of proximity-induced superconductivity in a candidate topological insulator. We have measured the bias-dependent differential conductance in Bi$_2$Se$_3$ nanoribbons contacted with superconducting electrodes over a temperature range 0.5 K $\leq T \leq$ 6 K in magnetic fields up to 8 T. We observe signatures of both proximity-induced superconductivity and incoherent multiple Andreev reflections in these mesoscale devices. In addition, we find periodic magneto- resistance oscillations for magnetic field perpendicular to both the nanoribbon axis and the superconducting contacts. The temperature- and field-dependence of the magneto-resistance oscillation amplitude and period are suggestive of dissipative vortex dynamics in the vicinity of the contacts. Supported by NSF-MRSEC, NSF-NNIN and ONR.

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Authors

  • D.M. Zhang

    • Physics Dept., Penn State University, University Park PA 16802

  • Jian Wang

    • Physics Department, Penn State University
    • Physics Dept., Penn State University, University Park PA 16802
    • Penn State University
    • Center for Nanoscale Science and Materials Research Institute, Penn State University, University Park PA 16802.
    • The Pennsylvania State University

  • J.S. Lee

    • Physics Dept., Penn State University, University Park PA 16802

  • H.R. Gutierrez

    • Physics Dept., Penn State University, University Park PA 16802

  • Moses Chan

    • The Pennsylvania State University
    • Physics Department, Penn State University
    • Pennsylvania State University
    • Physics Dept., Penn State University, University Park PA 16802
    • Penn State University

  • N. Samarth

    • Department of Physics and Materials Research Institute, The Pennsylvania State University, University Park, PA 16802
    • Physics Dept., Penn State University, University Park PA 16802
    • Pennsylvania State University
    • Department of Physics and Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
    • Center for Nanoscale Science and Materials Research Institute, Penn State University, University Park PA 16802.