Development of a magnetic interatomic potential for cubic antiferromagnets: The case of NiO

Abstract

Interatomic potentials are essential for molecular dynamics simulations of magnetic materials, yet incorporating magnetic features into potentials for complex antiferromagnets remains challenging. Nickel oxide (NiO), a prototypical cubic antiferromagnet, exemplifies this difficulty. Here, we develop a methodology to integrate magnetic properties into interatomic potentials for cubic antiferromagnets by adding a magnetic Hamiltonian, which includes both the Heisenberg exchange and the Néel model. We apply this approach to NiO by constructing two potentials: one based on the Born model of ionic solids and another using a reference-free modified embedded atom method. The models are validated against density functional theory calculations and experimental data, showing excellent agreement in mechanical and magnetic properties across both zero and finite temperatures, correctly capturing thermal expansion and the temperature dependence of elastic constants. Furthermore, we demonstrate the sensitivity of the potential to symmetry-breaking lattice distortions (tetragonal, shear, and trigonal), providing a predictive framework for controlling the Néel vector via strain engineering in antiferromagnetic spintronics. These models enable large-scale simulations of magnetoelastic phenomena in antiferromagnets and open avenues for molecular dynamics studies involving coupled electric and magnetic fields in metal oxides.