Unconventional Josephson effect in 2D Josephson junctions based on In0.75Ga0.25As quantum wells

ORAL

Abstract

Here, we report on the discovery of an unconventional Josephson effect in hybrid In0.75Ga0.25As two-dimensional electron gas-Nb junctions that are designed and fabricated for scalable hybrid quantum circuit integration [1-3]. By sweeping the in-plane magnetic field, we observe a completely new type of oscillation mechanism in the differential conductance, that has not been identified before. We find that the differential conductance as a function of source-drain voltage shows two symmetric in-gap resonances, which are strongly temperature and magnetic field dependent. The resonances amplitudes enhance with increasing in-plane magnetic fields up to a critical field where they gradually suppress and disappear. The observed supercurrent also gradually increases with applied magnetic field up to the same critical field. We believe that these striking observed behaviours in our devices-that cannot be explained by the conventional Josephson effect phenomenon- may be related to the context of topological superconductivity in hybrid 2D systems.
Reference:
[1] K. Delfanazari, et. al. Adv. Mater. 29, 1701836 (2017).
[2] K. Delfanazari, et. al. J. Magn. Magn. Mater. 459, 282-284 (2018).
[3] K. Delfanazari, et. al. IEEE Trans. Appl. Supercond. 28, 1100304 (2018).

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Presenters

  • Kaveh Delfanazari

    University of Cambridge

Authors

  • Kaveh Delfanazari

    University of Cambridge

  • Pengcheng Ma

    University of Cambridge

  • Ian Farrer

    University of Sheffield, Department of Physics, University of Cambridge, Electronic and Electrical Engineering, University of Sheffield, Electrical Engineering, University of Sheffield, Department of Electronic and Electrical Engineering, University of Sheffield, Physics, Sheffield University

  • David A Ritchie

    University of Cambridge, Department of Physics, University of Cambridge, Semiconductor Physics, University of Cambridge, Physics, University of Cambridge, Department of Physics, Cavendish Laboratory, Physics, Cambridge University

  • Hannah Joyce

    University of Cambridge

  • Michael Joseph Kelly

    University of Cambridge

  • Charles G Smith

    Department of Physics, University of Cambridge, University of Cambridge, Physics, Cambridge University