Magnetic Field Effect on the Evolution of the Magnon Population Properties in the [Co/Ag] Superlattice

In this work, the effect of applied magnetic field on the magnetic properties of Co/Ag] superlattice is studied in the framework of the theory of spin waves for ferromagnetic Heisenberg systems, where the exchange and the dipolar interactions and the magneto-crystalline and surface anisotropies are all taking into account. The obtained corresponding Hamiltonian is treated using Green’s functions method. The analytical expressions of the excitation spectrum and the magnetization per spin are obtained when the exchange is present alone. While in the case where the above-cited other interactions are also present, a numerical study is done. The adjustment of the results of calculated and measured magnetization per spin obtained for various magnetic layer thickness (t _Co) is good. The deduced values of the exchange integral J are in line of the values usually given for this type of superlattices based on 3d-transition metals. The combined effect of dipolar interactions and surface anisotropy is studied numerically.