We study the temperature evolution of quasiparticles in the correlated metal Sr2RuO4. Our angle resolved photoemission data show that quasiparticles persist up to temperatures above 200~K, far beyond the Fermi liquid regime. Extracting the quasiparticle self-energy we demonstrate that the quasiparticle residue Z increases with increasing temperature. Quasiparticles eventually disappear on approaching the bad metal state of Sr2RuO4 not by losing weight but via excessive broadening from super-Planckian scattering. We further show that the Fermi surface of Sr2RuO4 - defined as the loci where the spectral function peaks - deflates with increasing temperature. These findings are in semi-quantitative agreement with dynamical mean field theory calculations.
@article{arxiv.2308.02313,
title = {The fate of quasiparticles at high-temperature},
author = {A. Hunter and S. Beck and E. Cappelli and F. Margot and M. Straub and Y. Alexanian and G. Gatti and M. D. Watson and T. K. Kim and C. Cacho and N. C. Plumb and M. Shi and M. Radović and D. A. Sokolov and A. P. Mackenzie and M. Zingl and J. Mravlje and A. Georges and F. Baumberger and A. Tamai},
journal= {arXiv preprint arXiv:2308.02313},
year = {2023}
}