Theory of surface states in spin wave resonance

Abstract

Following a concise review of present achievements in the study of magnetic surface states by spin wave resonance, a discussion of surface state theory and experimentally observed effects is given. The theoretical treatment, starting from the general model assumptions made when dealing with thin magnetic films, concentrates specifically on the Surface Inhomogeneity Model, for which a Hamiltonian is established and diagonalized, leading to the elementary magnetic excitation i.e. spin waves of the system. The appropriate spin wave resonance theory is developed in detail, and the resonance effects are expounded on the basis of a Pinning Diagram, especially constructed for this purpose. Particular attention is given to the existence conditions for surface states, the experimental identification of their respective resonance lines, as well as the use of these lines when determining the surface conditions of the thin film and measuring its magnetic surface anisotropy. The analysis of the surface state properties is based on the exact solution of the eigenvalue problem of a finite linear chain with arbitrary (asymmetric) boundary conditions.