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.

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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