Nanoscale Electrostatic Control of Oxide Interfaces

TL;DR

This paper presents a new platform for nanoscale electrostatic control at oxide interfaces, enabling tunable confinement, superconducting transitions, and Josephson effects in LaAlO3/SrTiO3 systems across a wide temperature range.

Contribution

It introduces a robust top-gate architecture for oxide interfaces, allowing precise electrostatic manipulation of electronic phases at the nanoscale.

Findings

Nanoscale electron confinement achieved with patterned gates.

Local superconducting-insulating transition induced by a single gate.

Evidence of gate-controlled Josephson effect in superconducting regime.

Abstract

We develop a robust and versatile platform to define nanostructures at oxide interfaces via patterned top gates. Using LaAlO$_3$/SrTiO$_3$ as a model system, we demonstrate controllable electrostatic confinement of electrons to nanoscale regions in the conducting interface. The excellent gate response, ultra-low leakage currents, and long term stability of these gates allow us to perform a variety of studies in different device geometries from room temperature down to 50 mK. Using a split-gate device we demonstrate the formation of a narrow conducting channel whose width can be controllably reduced via the application of appropriate gate voltages. We also show that a single narrow gate can be used to induce locally a superconducting to insulating transition. Furthermore, in the superconducting regime we see indications of a gate-voltage controlled Josephson effect.