Mass transport of adsorbates near a discontinuous structural phase transition

TL;DR

This study investigates how adsorbed layers move near a sharp phase transition, revealing that domain wall dynamics lead to distinct propagating profiles, aligning with experimental and microscopic simulation results.

Contribution

It introduces a coarse-grained model focusing on domain wall motion to describe mass transport near a discontinuous phase transition.

Findings

Intermediate hexagonal phase nucleates and grows

Profiles bifurcate into two sharp propagating fronts

Results agree with experimental and microscopic simulations

Abstract

We study the mass transport dynamics of an adsorbed layer near a discontinuous incommensurate striped-honeycomb phase transition via numerical simulations of a coarse-grained model focusing on the motion of domain walls rather than individual atoms. Following an initial step profile created in the incommensurate striped phase, an intermediate hexagonal incommensurate phase nucleates and grows, leading to a bifurcation into two sharp profiles propagating in opposite directions as opposed to broad profiles induced by atomic diffusive motion. Our results are in agreement with recent numerical simulations of a microscopic model as well as experimental observations for the Pb/Si(111) adsorbate system.