Ultrafast Raman thermometry in driven YBa$_2$Cu$_3$O$_{6.48}$

TL;DR

This study uses time-resolved Raman scattering to measure lattice temperature changes in YBa2Cu3O6.48 during photo-induced superconductivity, revealing insights into the driven state's dynamics and decay.

Contribution

It introduces a method to quantify lattice temperature in photo-induced superconducting states, enhancing understanding of driven-dissipative systems in cuprates.

Findings

Lattice temperature increased by ~80 K during photo-induced superconductivity.

Quasi-particle temperature increased by nearly 200 K.

Provides quantitative data on the driven state's decay process.

Abstract

Signatures of photo-induced superconductivity have been reported in cuprate materials subjected to a coherent phonon drive. A 'cold' superfluid was extracted from the transient Terahertz conductivity and was seen to coexist with 'hot' uncondensed quasi-particles, a hallmark of a driven-dissipative system of which the interplay between coherent and incoherent responses are not well understood. Here, time resolved spontaneous Raman scattering was used to probe the lattice temperature in the photo-induced superconducting state of YBa2Cu3O6.48. An increase in lattice temperature of approximately 80 K was observed by measuring the time dependent Raman scattering intensity of an undriven 'spectator' phonon mode. This is to be compared with an estimated increase in quasi-particle temperatures of nearly 200 K. These temperature changes provide quantitative information on the nature of the driven state and its decay, and may provide a strategy to optimize this effect.