Dynamical Scaling and Planckian Dissipation Due to Heavy-Fermion Quantum Criticality

Abstract

We study dynamical scaling associated with a Kondo-breakdown quantum-critical point (KB QCP) of the periodic Anderson model, treated by two-site cellular dynamical mean-field theory (2CDMFT). In the quantum-critical region, the dynamical staggered-spin susceptibility exhibits ω/T scaling. We propose a scaling ansatz that describes this behavior and reveals Planckian dissipation for the longest-lived excitations. The current susceptibility follows the same scaling, leading to strange-metal behavior for the optical conductivity and resistivity. Importantly, this behavior is driven by strong short-ranged vertex contributions, not single-particle decay. This suggests that the KB QCP described by 2CDMFT is a novel (i.e., disorder-free) strange-metal fixed point. Our results for the optical conductivity match experimental observations on YbRh2Si2 and CeCoIn5. Published by the American Physical Society 2025