Gate-tunable superconducting weak link behavior in top-gated LaAlO3-SrTiO3

Abstract

We use a combination of global back-gating and local top-gating to define nanoscale devices in the two-dimensional electron gas at the LaAlO3-SrTiO3 interface, demonstrating an efficient way for much finer spatial control over the properties of the interface, as compared to back-gating alone. The devices show indications of an inhomogenous superconducting weak link. The variation of critical current with perpendicular magnetic field shows evidence of oscillations, which hints at Josephson coupling. The variation of the critical current and zero bias resistance with temperature is consistent with short, overdamped weak links. We show that the applied top-gate voltage provides a strong handle on the properties of these weak links. This technique can be an important tool to define a variety of device structures in this system, allowing us to probe the nature of superconductivity in the LaAlO3-SrTiO3 interface system in different ways.