Strong non-linear response of strange metals

TL;DR

This paper demonstrates that strange metals exhibit strong nonlinear transport responses, with a divergence in third order conductivity at low temperatures, revealing new insights into their scaling behavior and relaxation dynamics.

Contribution

It introduces a model showing divergence in third order conductivity in strange metals and explores frequency and orientation dependence to characterize their properties.

Findings

Third order conductivity diverges as 1/T at low temperatures.

Nonlinear responses in strange metals are significantly stronger than in Fermi liquids.

Frequency and orientation dependence reveal relaxation times of heat and electron distributions.

Abstract

We show that nonlinear transport responses in strange metals are strong, larger by a factor of $E_F/T$ than in Fermi liquids. Within the two-dimensional Yukawa-Sachdev-Ye-Kitaev model of a Fermi surface with a spatially random coupling to a critical scalar, the third order conductivity is found to diverge as $1/T$ at low $T$, indicating the existence of a voltage-temperature scaling regime in the conductance. Its frequency and orientation dependence contains information on relaxation times of heat and electron distribution deformations, providing a new set of tools to characterize strange metals.