Nonlinear transport in a photo-induced superconductor

TL;DR

This study demonstrates ultrafast transport measurements in a photo-induced superconductor, revealing nonlinear current-voltage behavior indicative of transient superconductivity and inhomogeneous phases, advancing understanding of non-equilibrium quantum materials.

Contribution

It introduces a novel experimental setup for ultrafast transport measurements in photo-induced superconductors, enabling direct observation of transient superconducting states.

Findings

Observation of nonlinear I-V characteristics in the transient state

Evidence of inhomogeneous superconducting phases connected by resistive links

Validation of transient superconductivity through transport measurements

Abstract

Optically driven quantum materials exhibit a variety of non-equilibrium functional phenomena [1-11], which are potentially associated with unique transport properties. However, these transient electrical responses have remained largely unexplored, primarily because of the challenges associated with integrating quantum materials into ultrafast electrical devices. Here, thin films of K3C60 grown by Molecular Beam Epitaxy were connected by coplanar terahertz waveguides to a series of photo-conductive switches. This geometry enabled ultrafast transport measurements at high current densities, providing new information on the photo-induced phase created in the high temperature metal by mid-infrared excitation [12-16]. Nonlinearities in the current-voltage charactersitics of the transient state validate the assignment of transient superconductivity, and point to an inhomogeneous phase in which superconducting regions of the sample are connected by resistive weak links [17-23]. This work opens up the possibility of systematic transport measurements in driven quantum materials, both to probe their properties and to integrate them into ultrafast optoelectronic platforms.