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.