Nonequilibrium critical relaxation at a first-order phase transition point

TL;DR

This study numerically investigates the nonequilibrium relaxation dynamics of a mixed-interaction Ising model at a first-order phase transition, revealing stretched exponential decay and power-law behaviors that suggest a continuous transition from a nonequilibrium perspective.

Contribution

It provides new insights into the nonequilibrium relaxation processes at a first-order transition, highlighting behaviors typically associated with continuous transitions.

Findings

Autocorrelation function approaches its limit via stretched exponential decay.

Magnetization relaxes to different values depending on initial magnetization.

Power-law relaxation observed near the transition point for certain initial states.

Abstract

We study numerically the nonequilibrium dynamical behavior of an Ising model with mixed two-spin and four-spin interactions after a sudden quench from the high-temperature phase to the first-order phase transition point. The autocorrelation function is shown to approach its limiting value, given by the magnetization in the ordered phase at the transition point, m_c, through a stretched exponential decay. On the other hand relaxation of the magnetization starting with an uncorrelated initial state with magnetization, m_i, approaches either m_c, for m_i>0.5, or zero, for m_i<0.5. For small m_i and for m_i slightly larger than 0.5 the relaxation of the magnetization shows an asymptotic power-law time dependence, thus from a nonequilibrium point of view the transition is continuous.