Vortex Tunneling and Critical State in an Oxide Heterostructure

TL;DR

This paper investigates vortex behavior in a two-dimensional superconductor on KTaO$_3$, revealing quantum tunneling, thermal activation, and vortex pinning effects through transport measurements.

Contribution

It demonstrates the observation of quantum vortex tunneling and detailed vortex dynamics in a 2D oxide superconductor, a novel experimental insight.

Findings

Identification of multiple vortex-mediated transport regimes

Observation of quantum tunneling of vortices

Rich vortex pinning configurations inferred from switching current histograms

Abstract

Two-dimensional superconductors offer an excellent platform for the study of vortex matter due to their low superfluid stiffness and inability to effectively screen applied magnetic fields. Here we explore vortices in a two-dimensional superconductor formed at the surface of the complex oxide KTaO$_3$. Multiple regimes of vortex-mediated transport are identified and studied, revealing switching behaviour attributed to nucleation of individual vortices. Analysis of this regime allows us to identify the quantum tunneling of vortices, which transitions to thermally activated behaviour at elevated temperatures. Magnetic field dependence reveals rich histograms of the switching currents which we attribute to different configurations of pinned vortices.