Spinodal-like scaling behavior after a temperature quench across the first-order phase transition in three-dimensional $q$-state Potts models

Abstract

We study the out-of-equilibrium spinodal-like behavior of three-dimensional (3D) $q$-state Potts models (for $q\ge 3$), observed when the temperature is quenched across the first-order transition (FOT) point $β_{\rm fo}=T_{\rm fo}^{-1}$. We consider a standard quench protocol, in which high-temperature configurations, thermalized at $β_i<β_{\rm fo}$, are driven across the FOT by a purely relaxational dynamics at $β>β_{\rm fo}$. We focus on the emergence of spinodal-like behaviors in the thermodynamic limit, associated with the dynamic phase change. We argue that, if the nucleation of smooth droplets is the relevant mechanism of the post-quench phase change, for sufficiently small $β_{\rm fo}-β_i>0$, the time-dependent energy density should scale in terms of $ρ= (\ln t)^{3/2} δ$, where $δ= β/β_{\rm fo}-1$, with a discontinuity at a particular value $ρ=ρ_s>0$. This implies the emergence of a spinodal-like behavior, whose time scale $τ$ increases exponentially as $\ln τ\approx (ρ_s/δ)^{2/3}$ in the limit $δ\to 0^+$. We present a numerical analysis of the quench protocol in the 3D $q=6$ Potts model, which supports the above spinodal-like scenario.