Spin–lattice simulations of cobalt and iron–cobalt alloys with LAMMPS*

We performed a parallel implementation of spin–lattice dynamics into Sandia’s LAMMPS molecular dynamics code. The approach augments the phase space with a classical spin vector to each magnetic atom, in addition to its position and momentum.
The interactions are derived from an analog of the usual molecular dynamics Hamiltonian, accounting for both the mechanical potential energy due to electron-mediated interatomic interactions and a magneto-mechanical potential. The latter accounts for the exchange interaction and spin-orbit coupling terms, which are responsible for the motion of spins and the coupling between the lattice vibrations and the magnetic degrees of freedom.
After checking this methodology on cobalt, we want to use it for the simulation of magnetoelastic sensors. These sensors are designed by depositing iron-cobalt (compositions between Co_0.7Fe_0.3 and Co_0.75Fe_0.25) layers.
In order to obtain better insights into the structural and magnetoelastic properties of these sensors, our approach will perform first-principles calculations within the spin-dependent density functional theory in order to derive the ad hoc magneto-mechanic potentials, and use them to perform large-scale magnetoelastic simulations.