Dipole-exchange spin waves in ferromagnetic stripes with inhomogeneous magnetization

Abstract

Realistic calculations of linear spin waves in thin ferromagnetic stripes are presented using a microscopic method based on a Hamiltonian approach. The theory, which is applicable to inhomogeneously magnetized samples, incorporates both the exchange and dipole-dipole interactions as well as effects of single-ion anisotropy and an external magnetic field applied either parallel or perpendicular to the stripe axis. This approach does not require the specification of phenomenological boundary conditions to study spin waves in these confined configurations. The Green's function theory is applied to Permalloy and nickel stripes to obtain the frequency, spatial distribution, and spectral intensity of discrete spin-wave modes. Through the spin-wave properties, the effective pinning parameters of the dynamic magnetization at the boundaries of the systems are deduced.