Correlations in nano-scale step fluctuations: comparison of simulation and experiments

TL;DR

This study compares kinetic Monte Carlo simulations and VT-STM experiments to analyze nano-scale step fluctuations on Pb(111), confirming diffusion-limited kinetics and exploring the temperature dependence of transport properties.

Contribution

It introduces a combined simulation and experimental approach to study step-edge fluctuations, highlighting the need for more complex models for accurate surface kinetics representation.

Findings

Correlation times scale with expected diffusion kinetics

Temperature dependence of transport properties measured and simulated

Effective energy barrier for edge fluctuations deduced

Abstract

We analyze correlations in step-edge fluctuations using the Bortz-Kalos-Lebowitz kinetic Monte Carlo algorithm, with a 2-parameter expression for energy barriers, and compare with our VT-STM line-scan experiments on spiral steps on Pb(111). The scaling of the correlation times gives a dynamic exponent confirming the expected step-edge-diffusion rate-limiting kinetics both in the MC and in the experiments. We both calculate and measure the temperature dependence of (mass) transport properties via the characteristic hopping times and deduce therefrom the notoriously-elusive effective energy barrier for the edge fluctuations. With a careful analysis we point out the necessity of a more complex model to mimic the kinetics of a Pb(111) surface for certain parameter ranges.