Spin-Lattice Dynamics of Magnetic Nanostructures: Domain Walls, Defects, DMI, and Machine-Learning Insights

Spin-Lattice Dynamics (SLD) simulations, implemented via LAMMPS, provide a powerful framework to study the coupled evolution of magnetization and lattice structure in complex magnetic nanosystems. Unlike micromagnetic approaches, SLD resolves atomic-scale features—such as defects, strain, and spin-lattice coupling—enabling unique insights into emergent phenomena. This talk will highlight three applications.

Magnetic domain wall (DW) motion in Fe nanowires can provide a simple system to understand a problem of technological relevance. In perfect single crystals motion proceeds in agreement with a simple analytic model, depending on anisotropy, exchange strength, damping and external field. When a defect is added to the NW, velocity behaves non-monotonically. Magnetization evolution during collision of Fe nanoparticles (NPs) has implications for some astrophysical scenarios: high velocity collisions lead to high pressure and phase transformations which cause a collapse of the magnetic moments. However, as the pressure wave is released and the temperature is reduced, magnetization can slowly bounce back.

Finally, skyrmions are topologically stable magnetic structures that hold great potential for spintronic device applications due to their unique properties and ability to store and process information. Lattice strain can modify the phase diagram of a 2D system of skyrmions at finite temperature under an external field, for in-plane and out-of-plane Dzyaloshinskii-Moriya interactions (DMI). We analyze the evolution of this system with Machine-Learning tools, and preliminary results indicate that number, size, velocity, diffusivity and stability of skyrmions can be controlled by mechanical strain. This can be explained by the relative change in the strength of ferromagnetic coupling and DMI as the lattice is deformed.

Some limitations and challenges will be discussed for all these simulations.

This work is the result of fruitful collaborations which will be highlighted during the presentation.