Modeling the magnetic properties of cobalt nanofilms as promising materials for spintronics devices

Abstract

A hybrid molecular dynamics and spin modeling approach using the SPIN package within the LAMMPS software suite was employed to investigate the influence of thickness on the magnetic properties of crystalline cobalt nanofilms with a face-centered cubic structure. Film thickness acts as a critical parameter determining magnetic behavior through the dynamic interplay of surface and bulk effects. In the region of ultrathin films (thickness less than 4.5 nm), a pronouncedly inhomogeneous magnetic response is observed, stemming from the dominance of surface effects. Key contributing factors include the influence of atomic-scale roughness, which creates local demagnetizing fields. This leads to complex domain wall dynamics, manifested as abrupt changes in magnetization and fine-scale non-uniformity in its spatial distribution. When the film thickness exceeds 4.5 nm, a transition to bulk-like behavior occurs. The reduction in the relative proportion of surface atoms allows the bulk properties of cobalt to come to the fore. Consequently, the dependence of magnetization on the external field becomes more pronounced and stable, while its spatial distribution exhibits increased uniformity. The normalized magnetic energy stabilizes at a level characteristic of the bulk material. The obtained results hold practical significance for the design of spintronics and magnetic recording devices. Furthermore, by understanding the magnetic interactions and dynamic responses of nanofilms, researchers and engineers can develop more efficient and reliable magnetic memory technologies, as well as novel spintronic components that leverage their unique magnetic characteristics for applications in sensing, data processing, and quantum information systems.