Numerical study of magnetic properties for Co-Fe-Nb nanofilms as promising materials for magnetoresistive memory

The paper presents an overview of the magnetic resistive memory varieties, discusses their design features, weaknesses and benefits, and provides a comparative characteristic. A review of a combined mathematical model that jointly describes the change of spins and coordinates of atoms (spin-lattice dynamics) is given. In general, the model can use any form of interatomic force potential and describes various contributions to the magnetic Hamiltonian. In this work, a simplified form of the magnetic Hamiltonian, taking into account only the Zeeman and exchange interactions, was considered to investigate magnetic interactions. The described model is implemented in the SPIN software package in the freely distributed LAMMPS complex. In this work, computational experiments were performed using the MEAM potential. The computational experiments represent three separate series of calculations. In the first one, the formation and structuring processes in a multilayer cobalt-iron-niobium nanocomposite were considered. It was shown that during the deposition of niobium, a rough nanofilm is formed, with height differences of several angstroms. It was noted that between the nanofilms of iron and niobium, the formation of a more diffuse contact zone was observed, compared to the contact of the layers of cobalt and iron. In the second version of the numerical experiments, the mutual self-ordering of directions and reorientation of spins in crystalline iron were analyzed, both in the presence of an external magnetic field and in its absence. During the simulation, the formation of vortex flows (skyrmions) was revealed. It was shown that under the influence of an external magnetic field an induced magnetic moment occurs in crystalline iron. Its direction is opposite to the direction of the magnetic induction vector of the applied field. The third numerical experiment was focused on modeling the magnetic properties of the cobalt-iron bilayer film under the conditions of a uniform external magnetic field. The formation of skyrmions was more typical for the Fe layer. Clearly defined magnetic domain regions were obtained in the cobalt nanofilm. It was revealed that the total magnetization of the Co-Fe system is low due to the absence of a clearly defined priority direction of the magnetic moments.