We use time-resolved thermometry to monitor the decay of nonequilibrium quasiparticles in superconducting Al in the temperature range from 0.3K to 1.2K. The quasiparticle lifetime at higher temperatures (T>0.7K) agrees well with the calculated energy flow from electrons to phonons, but at lower temperatures it is significantly shorter than the theory predicts. We show well-defined internal equilibrium of quasiparticle system in the studied thermal transients, which implicates that quasiparticle-quasiparticle relaxation is much faster than electron-phonon interaction.
@article{arxiv.2411.16614,
title = {Intrinsic Quasiparticle Lifetime in a Superconducting Aluminum},
author = {Konrad Norowski and Marek Foltyn and Alexander Savin and Maciej Zgirski},
journal= {arXiv preprint arXiv:2411.16614},
year = {2024}
}