It has recently been conjectured that the transport relaxation rate in metals is bounded above by the temperature of the system. In this work, we discuss the transport phenomenology of overdoped electron-doped cuprates, which we show constitute an unambiguous counterexample to this putative "Planckian" bound, raising serious questions about the efficacy of the bound.
@article{arxiv.2109.00513,
title = {A counterexample to the conjectured Planckian bound on transport},
author = {Nicholas R. Poniatowski and Tarapada Sarkar and Ricardo P. S. M. Lobo and Sankar Das Sarma and Richard L. Greene},
journal= {arXiv preprint arXiv:2109.00513},
year = {2021}
}