Dipolar spin-wave modes of a ferromagnetic multilayer with alternating directions of magnetization

Abstract

The spin-wave spectrum of a ferromagnetic multilayer with alternating directions of magnetization is derived in the dipolar magnetostatic limit. The external magnetic field is set equal to zero and the magnetization is assumed to be in-plane but reversed in adjacent films. We find interesting qualitative differences for an even and an odd number N of single layers which constitute the multilayer. The solutions can be classified as bulklike or surfacelike with respect to the whole multilayer. As N→∞ the bulklike solutions form bands. We also discuss some symmetry aspects of these solutions.