Photoinduced melting of superconductivity in the high-Tc superconductor La2-xSrxCuO4 probed by time-resolved optical and THz techniques

TL;DR

This study investigates how ultrafast optical and THz pulses can transiently suppress and recover superconductivity in La2-xSrxCuO4 films, revealing energy transfer dynamics and the non-thermal nature of the suppression.

Contribution

It provides new insights into the energy transfer processes during photoinduced suppression of superconductivity, showing most energy goes to phonons rather than breaking Cooper pairs.

Findings

Suppression energy density is about 8 times the thermodynamic condensation energy.

Superconductivity suppression occurs in approximately 0.7 ps.

Most energy (around 90%) transfers to low-energy phonons during suppression.

Abstract

Dynamics of depletion and recovery of superconducting state in La2-xSrxCuO_4 thin films is investigated utilizing optical pump-probe and optical pump - THz probe techniques as a function of temperature and excitation fluence. The absorbed energy density required to suppress superconductivity is found to be about 8 times higher than the thermodynamically determined condensation energy density and nearly temperature independent between 4 and 25 K. These findings indicate that during the time when superconducting state suppression takes place (~0.7 ps), a large part (nearly 90%) of the energy is transferred to the phonons with energy lower than twice the maximum value of of the SC gap and only 10% is spent on Cooper pair breaking.