Phase transition at finite temperature in one dimension: Adsorbate ordering in Ba/Si(111)3x2

TL;DR

This paper models Ba/Si(111)3x2 surface reconstruction as a 1D antiferromagnetic Ising system with Coulomb interactions, demonstrating a finite-temperature phase transition detectable via electron diffraction.

Contribution

It introduces a Coulomb-gas model based on density-functional calculations to describe adsorbate ordering in a one-dimensional surface reconstruction.

Findings

Finite-temperature phase transition identified in the model.

Monte Carlo simulations confirm the transition's characteristics.

Predicted experimental detection via low-energy electron diffraction.

Abstract

We demonstrate that the Ba-induced Si(111)3x2 reconstruction is a physical realization of a one-dimensional antiferromagnetic Ising model with long-range Coulomb interactions. Monte Carlo simulations performed on a corresponding Coulomb-gas model, which we construct based on density-functional calculations, reveal an adsorbate-ordering phase transition at finite temperature. We show numerically that this unusual one-dimensional phase transition should be detectable by low-energy electron diffraction.