Suppression of spinodal instability by disorder in an athermal system

TL;DR

This study investigates how disorder influences spinodal instability suppression in an athermal system, revealing asymmetric critical dynamics during a metal-insulator transition in a MnNiSn alloy, supported by experimental and simulation evidence.

Contribution

It demonstrates that disorder suppresses spinodal instabilities in an athermal transition, supported by experimental observations and ZTRFIM simulations.

Findings

Enhanced critical features during cooling transition

Disorder triggers heterogeneous nucleation before spinodal point

Disorder smears spinodal instabilities, limiting correlation length

Abstract

We observed asymmetric critical slowing down and asymmetric dynamical scaling exponent in the superheating and supercooling kinetic processes during the thermally-induced metal-insulator transition of MnNiSn based heusler alloy. During the transition to the insulator phase, the critical-like features get enhanced compared to the transition back to the metal phase. These experimental findings suggest that the metastable phase in the cooling branch of hysteresis has approached close to the spinodal instability. On the other hand, the extended disorder, generated over and above the intrinsic crystal defects during heating, triggers the excess heterogeneous nucleation before reaching the spinodal point. Zero temperature random field Ising model (ZTRFIM) simulation, inscribed for the athermal martensitic transitions, support the argument that the disorder smears the spinodal instabilities as the correlation length is bounded by the average distance between the disorder points.