Probing optically driven K₃C₆₀ thin films with an ultrafast voltmeter.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Optics

Background:

• Optically enhanced superconductivity in K3C60 is observed but its underlying physics and relation to equilibrium superconductivity remain unclear.
• Understanding the dynamics of photo-induced superconductivity is crucial for novel quantum electronic applications.

Purpose of the Study:

• To investigate the ultrafast voltage response of optically driven K3C60 thin films.
• To elucidate the role of granularity in photo-induced transport phenomena.
• To explore the potential for optoelectronic device applications.

Main Methods:

• Utilized ultrafast nonlinear transport measurements with photo-conductive switches.
• Measured time-resolved voltage changes in K3C60 thin films below and above the critical temperature (Tc).
• Analyzed data considering granular effects, kinetic inductance, and Josephson dynamics.

Main Results:

• Observed fast voltage changes attributed to in-grain carrier kinetic inductance.
• Identified a slower voltage response potentially linked to Josephson dynamics at weak links.
• Estimated in-grain photo-induced superfluid density and phase slip dynamics.

Conclusions:

• Granularity plays a significant role in the photo-induced transport response of K3C60.
• Ultrafast electrical measurements provide new insights into optically driven quantum materials.
• K3C60 presents a promising platform for ultrafast optoelectronic devices.