Quantum ground states which arise at atomically controlled oxide interfaces provide an opportunity to address key questions in condensed matter physics, including the nature of two-dimensional (2D) metallic behaviour often observed adjacent to superconductivity1-8. At the superconducting LaAlO3/SrTiO3interface9,10, a metallic ground state emerges upon the collapse of superconductivity with field-effect gating11,12. Strikingly, such metallicity is accompanied with a pseudogap13. Here, we utilize independent control of carrier density and disorder of the interfacial superconductor using dual electrostatic gates14, which enables the comprehensive examination of the electronic phase diagram approaching zero temperature. We find that the pseudogap corresponds to precursor pairing, and the onset of long-range phase coherence forms a 2D superconducting dome as a function of the dual gate voltages. The gate-tuned superconductor-metal transitions are driven by macroscopic phase fluctuations of Josephson coupled superconducting puddles.
|Publication status||Published - 2018 Jul 22|
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