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Free keywords:
Condensed Matter, Superconductivity, cond-mat.supr-con, Condensed Matter, Strongly Correlated Electrons, cond-mat.str-el
Abstract:
The physics of optically-induced superconductivity remains poorly understood, with questions that range from the underlying microscopic mechanism to the macroscopic electrical response of the non-equilibrium phase. In this paper, we study optically-induced superconductivity in K3C60 thin films, which display signatures of granularity both in the equilibrium state below Tc and in the nonequilibrium photo-induced phase above Tc. Photo-conductive switches are used to measure the ultrafast voltage drop across a K3C60 film as a function of time after irradiation, both below and above Tc. These measurements reveal fast changes associated with the kinetic inductance of in-grain superconductivity, and a slower response attributed to the Josephson dynamics at the weak links. Fits to the data yield estimates of the in-grain photo-induced superfluid density after the drive and the dynamics of phase slips at the weak links. This work underscores the increasing ability to make electrical measurements at ultrafast speeds in optically-driven quantum materials, and demonstrates a striking new platform for optoelectronic device applications.
