Strong Mpemba Effect Through a Reentrant Phase Transition

TL;DR

This study demonstrates the strong Mpemba effect in the antiferromagnetic Ising model, linking anomalous relaxation phenomena to reentrant phase transitions and the excitation of slow relaxation modes.

Contribution

First demonstration of the strong Mpemba effect in the antiferromagnetic Ising model using pair-approximation, connecting relaxation anomalies to phase behavior.

Findings

Strong Mpemba effect occurs when quenches end in the paramagnetic phase.

The effect is due to excitation of the slowest relaxation mode, which is purely staggered.

Disappearance of the effect correlates with the absence of reentrance in phase transition.

Abstract

We investigate temperature quenches across the reentrant phase transition of the antiferromagnetic Ising model in a magnetic field and show that the strong direct and inverse Mpemba effects arise when quenches terminate in the paramagnetic phase. These anomalous relaxation phenomena originate from the selective excitation of the slowest relaxation mode, which in the paramagnetic phase is purely staggered. Consequently, quenches starting from the paramagnetic phase have zero overlap with the slow mode and exhibit a strong (inverse) Mpemba effect. Quenches from the antiferromagnetic phase excite the staggered mode and display a slow-relaxation tail. By varying the lattice coordination number we show that the strong Mpemba effect disappears in the absence of reentrance. Our results provide the first demonstration of the strong (inverse) Mpemba effect in the antiferromagnetic Ising model based on the pair-approximation, and establish a link between anomalous relaxation and the equilibrium phase behavior.