Quantum interference in an interfacial superconductor

Abstract

The two-dimensional superconductor formed at the interface between the complex oxides, lanthanum aluminate (LAO) and strontium titanate (STO) has several intriguing properties that set it apart from conventional superconductors. Most notably, an electric field can be used to tune its critical temperature (T${}_c$), revealing a dome-shaped phase diagram reminiscent of high T${}_c$ superconductors. So far, experiments with oxide interfaces have measured quantities which probe only the magnitude of the superconducting order parameter and are not sensitive to its phase. Here, we perform phase-sensitive measurements by realizing the first superconducting quantum interference devices (SQUIDs) at the LAO/STO interface. Furthermore, we develop a new paradigm for the creation of superconducting circuit elements, where local gates enable in-situ creation and control of Josephson junctions. These gate-defined SQUIDs are unique in that the entire device is made from a single superconductor with purely electrostatic interfaces between the superconducting reservoir and the weak link. We complement our experiments with numerical simulations and show that the low superfluid density of this interfacial superconductor results in a large, gate-controllable kinetic inductance of the SQUID. Our observation of robust quantum interference opens up a new pathway to understand the nature of superconductivity at oxide interfaces.

Version prior to peer review. Final version published in Nature Nanotechnology

References in corpus (6)

• Electric Field Control of the LaAlO${}_3$/SrTiO${}_3$ Interface Ground State
• Bipolar supercurrent in graphene
• Tunable Supercurrent Through Semiconductor Nanowires
• Supercurrent reversal in quantum dots
• 0-pi Josephson tunnel junctions with ferromagnetic barrier
• Nanoscale Electrostatic Control of Oxide Interfaces

Cited by in corpus (23)

• Photoferroelectric oxides
• Physics of SrTiO${}_3$-based heterostructures and nanostructures: a review
• Imaging and tuning polarity at SrTiO3 domain walls
• Field-Effect Controllable Metallic Josephson Interferometer
• Gate-tunable band structure of the LaAlO${}_3$-SrTiO${}_3$ interface
• A Tunable Monolithic SQUID in Twisted Bilayer Graphene
• Side gate tunable Josephson junctions at the LaAlO${}_3$/SrTiO${}_3$ interface
• Link between supercurrent diode and anomalous Josephson effect revealed by gate-controlled interferometry
• Superconducting quantum point contact with split gates in the two dimensional LaAlO3/SrTiO3 superfluid
• rf-SQUID measurements of anomalous Josephson effect
• Dynamic properties of high-Tc superconducting nano-junctions made with a focused helium ion beam
• Correlation between Superconductivity, Band Filling and Electron Confinement at the LaAlO${}_3$-SrTiO${}_3$ Interface
• Bimodal Phase Diagram of the Superfluid Density in LaAlO3/SrTiO3 Revealed by an Interfacial Waveguide Resonator
• Gate-tunable superconductivity at SrTiO3 surface realized by Al layer evaporation
• Intrinsic magnetism in KTaO${}_3$ heterostructures
• Gate-tunable, normally-on to normally-off memristance transition in patterned LaAlO3/SrTiO3 interfaces
• Superconducting quantum oscillations and anomalous negative magnetoresistance in a honeycomb nanopatterned oxide interface superconductor
• Electronic transport in sub-micrometric channels at the LaAlO${}_3$/SrTiO${}_3$ interface
• Quantum oscillations in an optically-illuminated two-dimensional electron system at the LaAlO${}_3$/SrTiO${}_3$ interface
• Mixed superconducting state without applied magnetic field
• Strong Aharonov-Bohm quantum interference in simply-connected LaAlO${}_3$/SrTiO${}_3$ structures
• Electrostatic gate-controlled quantum interference in a high-mobility two-dimensional electron gas at the (La${}_{0.3}$Sr${}_{0.7}$)(Al${}_{0.65}$Ta${}_{0.35}$)O${}_3$/SrTiO${}_3$ interface
• Origin of the dome-shaped superconducting phase diagram in ${\mathrm{SrTiO}}_3$-based interfaces