Coupled structural and magnetic properties of ferric fluoride nanostructures part I: a Metropolis atomistic study

TL;DR

This paper introduces a modified Monte Carlo simulation method to model grain boundary structures in ionic nanostructures, specifically iron trifluoride, revealing the importance of long-range Coulombic interactions for accurate structural and magnetic property predictions.

Contribution

It develops a novel atomistic simulation approach for ionic nanostructures that accurately models grain boundaries without periodic boundary conditions, incorporating long-range Coulombic effects.

Findings

Accurate grain boundary structures matching experimental properties.

Long-range Coulombic interactions are essential for realistic modeling.

Structural features influence local magnetic configurations.

Abstract

A modified Metropolis atomistic simulation is proposed to model the structure of grain boundaries (GBs) and interfaces in ionic nanostructured systems and is applied to the magnetically interesting case of iron trifluoride (FeF3). We chose long-range interatomic potentials adjusted on experimental results, and adapted a previously established Monte Carlo scheme consisting of various modifications of the simulated annealing/ Metropolis algorithm. Atomic structures of twisted and tilted GBs as a function of the relative disorientation of the grains have been achieved yielding close to experimentally measured properties. This approach takes into account the structure of the grains far from the interface in order to constrain the relative orientation of the grains, without any periodic boundary conditions. One concludes that a long-range coulombic falloff of the interatomic potentials is necessary to obtain GB structures presenting a correct local topology but with a smooth transition from crystalline to amorphous states. The structural features are finally discussed in terms of topological aspects and local magnetic structure.