Relaxation electrodynamics of superinsulators

TL;DR

This paper investigates the non-equilibrium relaxation dynamics of superinsulators, revealing critical exponents that confirm electric string confinement and distinguish it from disorder-induced localization, thus advancing understanding of strong interaction phenomena in quantum materials.

Contribution

It provides experimental evidence for electric string confinement in superinsulators and characterizes their relaxation dynamics, distinguishing them from localization effects.

Findings

Power-law relation between delay time and voltage with two critical exponents.

Confirmation of electric string confinement through the $rac{1}{2}$ exponent.

Observation of memory effects and dynamic critical exponents.

Abstract

Superinsulators offer a unique laboratory realizing strong interaction phenomena like confinement and asymptotic freedom in quantum materials. Recent experiments evidenced that superinsulators are the mirror-twins of superconductors with reversed electric and magnetic field effects. Cooper pairs and Cooper holes in the superinsulator are confined into neutral electric pions by electric strings, with the Cooper pairs playing the role of quarks. Here we report the non-equilibrium relaxation of the electric pions in superinsulating films. We find that the time delay $t_{\mathrm{sh}}$ of the current passage in the superinsulator is related to the applied voltage $V$ via the power law, $t_{\mathrm{sh}}\propto (V-V_{\mathrm p})^{-\mu}$, where $V_{\mathrm p}$ is the effective threshold voltage. Two distinct critical exponents, $\mu=1/2$ and $\mu=3/4$, correspond to jumps from the electric Meissner state to the mixed state and to the superinsulating resistive state with broken charge confinement, respectively. The $\mu=1/2$ value establishes a direct experimental evidence for the electric strings' linear potential confining the charges of opposite signs in the electric Meissner state and effectively rules out disorder-induced localization as a mechanism for superinsulation. We further report the memory effects and their corresponding dynamic critical exponents arising upon the sudden reversal of the applied voltage. Our observations open routes for exploring fundamental strong interaction charge confinement via desktop experiments.