Electrostatically defined superconducting quantum interference devices at the LaAlO$_3$/SrTiO$_3$ interface

ORAL

Abstract

Two-dimensional superconductivity at the LaAlO$_3$ (LAO)/ SrTiO$_3$ (STO) interface can be controlled via the field effect, whereby a global back gate can be used to systematically tune the critical temperature (T$_c$) of the bulk superconductor. Here, we exploit this sensitivity of T$_c$ to the field effect to create an electrostatically defined superconducting quantum interference device (SQUID) at the LAO/STO interface. The device consists of a superconducting loop with nanoscale local top gates on each arm. By controllably depleting carriers below the gates we create a SQUID with two identical Josephson junctions (JJs), giving rise to flux-periodic oscillations in the critical current. Furthermore, by independently tuning the two JJs we create an asymmetric SQUID, which allows us to accurately estimate an extremely large kinetic inductance of about 60nH. While other examples of gate-tunable JJs do exist, they necessarily involve physical interfaces between two dissimilar materials. In contrast, our gate-defined SQUIDs are unique in that the entire device is made from a single superconductor with purely electrostatic interfaces.

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Authors

  • Srijit Goswami

    Kavli Institute of Nanoscience, Delft University of Technology,The Netherlands, Kavli Institute of Nanoscience, Delft University of Technology, The Netherlands

  • Emre Mulazimoglu

    Kavli Institute of Nanoscience, Delft University of Technology,The Netherlands, Kavli Institute of Nanoscience, Delft University of Technology, The Netherlands

  • Ana M. R. V. L. Monteiro

    Kavli Institute of Nanoscience, Delft University of Technology,The Netherlands, Kavli Institute of Nanoscience, Delft University of Technology, The Netherlands

  • Roman Woelbing

    Physikalisches Institut - Experimentalphysik II, Eberhard Karls Universitaet Tuebingen, Germany, Physikalisches Institut - Experimentalphysik II, Eberhard Karls Universitat Tuebingen, Germany

  • Dieter Koelle

    Physikalisches Institut - Experimentalphysik II, Eberhard Karls Universitaet Tuebingen, Germany, Physikalisches Institut - Experimentalphysik II, Eberhard Karls Universitat Tuebingen, Germany, University of Tuebingen

  • Reinhold Kleiner

    Physikalisches Institut - Experimentalphysik II, Eberhard Karls Universitaet Tuebingen, Germany, Physikalisches Institut - Experimentalphysik II, Eberhard Karls Universitat Tuebingen, Germany, University of Tuebingen

  • Yaroslav Blanter

    Kavli Institute of Nanoscience, Delft University of Technology,The Netherlands

  • Lieven Vandersypen

    Kavli Institute of Nanoscience, Delft University of Technology,The Netherlands, QuTech and Kavli Institute of Nanoscience

  • Andrea Caviglia

    Kavli Institute of Nanoscience TU Delft, Kavli Institute of Nanoscience, Delft University of Technology,The Netherlands