Transparent Contacts between Quantum Anomalous Hall Insulators and Superconductors

ORAL

Abstract

A quantum anomalous Hall (QAH) insulator coupled to an s-wave superconductor is predicted to harbor a chiral topological superconducting phase, the elementary excitations of which (i.e. chiral Majorana fermions) upon non-Abelian braiding operations can form topological quantum qubits. Here, we fabricated the QAH/Nb hybrid heterostructures and first studied their two-terminal conductance. We found that the two-terminal conductance constantly shows a half-quantized value in the entire range of the magnetic field where the magnetization is well-aligned. Next, we studied the contact transparency between the QAH and Nb films. When the QAH layer is tuned to the metallic regime by gating, we observed Andreev reflections, i.e., a large enhancement of the resistance when a DC bias voltage across the magnetic TI/Nb junction is increased above the Nb superconducting gap. This observation indicates a transparent interface between the QAH and Nb layers. Our study provides a more comprehensive understanding of the relation between the superconducting proximity effect and the observation of the half quantized two-terminal conductance in the QAH/Nb hybrid structure.

*This work is supported by ARO grant (W911NF1810198), Alfred P. Sloan Research Fellowship, 2DCC-MIP, ONR, and ARO MURI.

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Presenters

  • Morteza Kayyalha

    • Physics, Penn State University
    • Department of Physics, Pennsylvania State University
    • Pennsylvania State University

Authors

  • Morteza Kayyalha

    • Physics, Penn State University
    • Department of Physics, Pennsylvania State University
    • Pennsylvania State University

  • Di Xiao

    • Physics, Penn State University
    • Physics, The Pennsylvania State University
    • Department of Physics, The Pennsylvania State University
    • Pennsylvania State University
    • Department of Physics, Pennsylvania State University

  • Ruoxi Zhang

    • Pennsylvania State University

  • Jaeho Shin

    • Department of Physics, Pennsylvania State University
    • Pennsylvania State University

  • Jue Jiang

    • Department of Physics, Pennsylvania State University
    • Department of Physics, The Pennsylvania State University
    • Pennsylvania State University

  • Fei Wang

    • Physics, Penn State University
    • Pennsylvania State University

  • Yifan Zhao

    • Department of Physics, Pennsylvania State University
    • Department of Physics, The Pennsylvania State University
    • Pennsylvania State University

  • Ling Zhang

    • Physics, Penn State University
    • Department of Physics, Pennsylvania State University
    • Physics, The Pennsylvania State University
    • Department of Physics, The Pennsylvania State University
    • Pennsylvania State University

  • Chao-Xing Liu

    • Pennsylvania State University
    • Physics, The Pennsylvania State University
    • Department of Physics, The Pennsylvania State University
    • Department of Physics, Pennsylvania State University

  • Qi Li

    • Pennsylvania State University

  • Moses H. W. Chan

    • Department of Physics, Pennsylvania State University
    • Physics, The Pennsylvania State University
    • Department of Physics, The Pennsylvania State University
    • Pennsylvania State University

  • Nitin Samarth

    • Department of Physics and Materials Research Institute, Pennsylvania State University
    • Physics, Penn State University
    • Physics, The Pennsylvania State University
    • Pennsylvania State University
    • Department of Physics, Pennsylvania State University
    • Materials Research Institute, Pennsylvania State University
    • Department of Physics, The Pennsylvania State University
    • Physics, Pennsylvania State University

  • Cui-Zu Chang

    • Pennsylvania State University
    • Physics, Penn State University
    • Department of Physics, Pennsylvania State University
    • Physics, The Pennsylvania State University
    • Department of Physics, The Pennsylvania State University