Ultrafast dynamics of fluctuations in high-temperature superconductors far from equilibrium

TL;DR

This study investigates the ultrafast nonequilibrium dynamics of high-temperature superconductors, revealing universal power-law relaxation behavior above the critical temperature and advancing understanding of fluctuation regimes.

Contribution

It demonstrates the first direct measurement of nonequilibrium fluctuation dynamics in high-Tc superconductors using femtosecond spectroscopy, highlighting universal scaling laws.

Findings

Power-law relaxation observed above Tc

Universal scaling behavior in different doping regimes

Modeling supported by time-dependent Ginzburg-Landau theory

Abstract

Despite extensive work on high-temperature superconductors, the critical behavior of an incipient condensate has so far been studied exclusively under equilibrium conditions. Here, we excite Bi2Sr2CaCu2O8+d with a femtosecond laser pulse and monitor the subsequent nonequilibrium dynamics of the mid-infrared conductivity. Our data allow us to discriminate temperature regimes where superconductivity is either coherent, fluctuating or vanishingly small. Above the transition temperature Tc, we make the striking observation that the relaxation to equilibrium exhibits power-law dynamics and scaling behavior, both for optimally and underdoped superconductors. Our findings can in part be modeled using time-dependent Ginzburg-Landau theory and provide strong indication of universality in systems far from equilibrium.