Measurements of the gate tuned superfluid density in superconducting LaAlO3/SrTiO3

TL;DR

This study measures how the superfluid density in LaAlO3/SrTiO3 interfaces varies with temperature and gate voltage, revealing a consistent superconducting gap and unmodulated dipole moments, advancing understanding of gate-tunable superconductivity.

Contribution

It provides the first local magnetic susceptibility measurements of superfluid density as a function of gate voltage in LaAlO3/SrTiO3, showing a universal temperature dependence and unaltered dipole moments.

Findings

Superfluid density follows a universal temperature dependence at different gate voltages.

Gate voltage does not modulate the observed dipole moments.

Superfluid density indicates a full superconducting gap.

Abstract

The interface between the insulating oxides LaAlO3 and SrTiO3 exhibits a superconducting two-dimensional electron system that can be modulated by a gate voltage. While gating of the conductivity has been probed extensively and gating of the superconducting critical temperature has been demonstrated, the question whether, and if so how, the gate tunes the superfluid density and superconducting order parameter is unanswered. We present local magnetic susceptibility, related to the superfluid density, as a function of temperature, gate voltage and location. We show that the temperature dependence of the superfluid density at different gate voltages collapse to a single curve characteristic of a full superconducting gap. Further, we show that the dipole moments observed in this system are not modulated by the gate voltage.