Quantum critical fluctuations may prove to play an instrumental role in the formation of unconventional superconductivity. Here, we show that the characteristic scaling of a marginal Fermi liquid is present in inelastic light scattering data of an Fe-based superconductor tuned through a quantum critical point (QCP) by chemical substitution or doping. From the doping dependence of the imaginary time dynamics we are able to distinguish regions dominated by quantum critical behavior from those having classical critical responses. This dichotomy reveals a connection between the marginal Fermi liquid behavior and quantum criticality. In particular, the overlap between regions of high superconducting transition temperatures and quantum critical scaling suggests a contribution from quantum fluctuations to the formation of superconductivity.
@article{arxiv.2111.07521,
title = {Quantum critical fluctuations in an Fe-based superconductor},
author = {Daniel Jost and Leander Peis and Ge He and Andreas Baum and Stephan Geprägs and Johanna C. Palmstrom and Matthias S. Ikeda and Ian R. Fisher and Thomas Wolf and Samuel Lederer and Steven A. Kivelson and Rudi Hackl},
journal= {arXiv preprint arXiv:2111.07521},
year = {2022}
}