Apparent Planckian scattering from local polaron formation

TL;DR

This paper introduces a mechanism where local polaron formation causes apparent Planckian scattering, demonstrated through Monte Carlo simulations, revealing a regime with a constant slope in scattering rate and violation of Matthiessen's rule.

Contribution

The authors propose a universal mechanism linking polaron formation to Planckian scattering, supported by simulations, and applicable to disordered systems with polaronic interactions.

Findings

The scattering rate follows aaaa aaaa aaaa aaaa a0000 aaaa aaaa aaaa aaaa aaaa aaaa a0000 in a regime of local polaron formation.

The slope aaaa remains approximately constant over a range of couplings, indicating a universal behavior.

Matthiessen's rule is violated or obeyed depending on the perspective, with changes in couplings affecting the intercept rather than the slope.

Abstract

We propose a simple mechanism for apparent Planckian scattering based on local polaron formation, in which $\Gamma_\text{tr} = \Gamma_0 + \alpha k_BT / \hbar$ with $\alpha \sim O(1)$ emerges from quasielastic scattering without fine tuning. We provide evidence for our proposal in Monte Carlo simulations of the Holstein model with disordered electron-phonon coupling in the adiabatic limit. Our mechanism generates a finite interval of couplings in which the slope $\alpha$ is approximately constant, coinciding with the onset of local polaron formation. In this regime, Matthiessen's rule is dramatically violated (or obeyed, depending on one's point of view) in that changes to the couplings, which in perturbation theory would alter the slope $\alpha$, instead change the intercept $\Gamma_0$. We conjecture that a version of our mechanism applies to any system with a dominant disordered interaction that can drive polaron formation. This potentially includes regimes of the recently introduced disordered-Yukawa-coupling strange metal models where polaron formation is not suppressed.