Planckian scattering—a linear-in-temperature scattering rate Γ ≈ kT/ℏ—is among the most striking and widely discussed signatures of strange metals. Why the scattering rate has this universal form across disparate systems, ranging from the cuprates to magic-angle bilayer graphene and even some conventional metals, is a central question in condensed matter physics.

I will discuss recent theoretical work in which we propose a simple mechanism by which apparent Planckian scattering can emerge from the coexistence of itinerant carriers and self-trapped polarons in systems with disordered interactions. We provide evidence for our proposal in Monte Carlo simulations of lattice models with disordered electron-boson coupling in the adiabatic limit. We find a finite interval of couplings in which Γ is T-linear with an approximately constant O(1) slope, 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, instead change the intercept Γ_0. We conjecture that a version of the mechanism applies to any system with a dominant disordered interaction that can drive polaron formation. This potentially includes regimes of several recently introduced strange metal models based on spatially random interactions.