A charge optimized many-body potential for iron/iron-fluoride systems.

Area of Science:

• Materials Science
• Computational Chemistry
• Condensed Matter Physics

Background:

• Developing accurate interatomic potentials is crucial for simulating complex material behaviors.
• Iron and iron-fluoride systems are relevant in various technological applications, necessitating precise modeling.
• Understanding interface phenomena is key to controlling material properties.

Purpose of the Study:

• To develop a classical interatomic potential for iron/iron-fluoride systems using the charge optimized many-body (COMB) framework.
• To incorporate charge transfer and environment-dependent many-body interactions into the potential.
• To investigate interface properties and their relation to exchange bias in FeF2/Fe systems.

Main Methods:

• Development of a COMB potential fitted to experimental and ab initio data for cohesive energies, lattice parameters, and elastic constants.
• Atomistic simulations using an NVT ensemble for various configurations including bulk phases, molecules, clusters, and nanostructures.
• Modeling of FeF2/Fe interfaces and nanowires to study atomic rearrangements and charge transfer.

Main Results:

• The developed potential accurately reproduces cohesive energies, lattice parameters, and elastic constants for Fe and FeF2.
• Simulations show atomic reordering at FeF2/Fe interfaces, leading to enhanced charge transfer.
• A mechanism for exchange bias is proposed, linked to asymmetric electric charge transfer across spin channels at interfaces.

Conclusions:

• The COMB potential provides a reliable tool for simulating iron/iron-fluoride systems.
• Interface atomic rearrangements and charge transfer play a significant role in the magnetic properties of these systems.
• The findings offer insights into the origin of exchange bias in magnetic heterostructures.